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RADIATION INSTITUTE, for JEE (Main & Adv.)/NEET, FOUNDATION, PRE-FOUNDATION with Board,, Electrostatics, , Charge and Coulomb’s Law, 1., , 2., , There are two charges +1 microcoulombs and +5 microcoulombs., The ratio of the forces acting on them will be, , 10., , (b) 1 : 1, (d) 1 : 25, , (d) Perpendicular to side AB, , The minimum charge on an object is, (a) 1 coulomb, (c), , 12., , Fg and Fe represents gravitational and electrostatic force, respectively between electrons situated at a distance 10 cm. The ratio, of Fg / Fe is of the order of, , (d), , 3.2  10 19 coulomb, , Out of gravitational, electromagnetic, Vander Waals, electrostatic, and nuclear forces; which two are able to provide an attractive force, between two neutrons, (a) Electrostatic and gravitational, (b) Electrostatic and nuclear, (c) Gravitational and nuclear, , (b) 10, , (c) 1, (d) 10 43, The ratio of the forces between two small spheres with constant, charge (a) in air (b ) in a medium of dielectric constant K is, (a) 1 : K, , 1.6  10 19 coulomb, , (b) 1 stat coulomb, , [NCERT 1978], , [NCERT 1978; CPMT 1978], 10 42, , [CPMT 1972; AIIMS 1998], , (c) Giving some protons to it, [NCERT, 1971]from it, (d) Removing some, neutrons, 11., , (d) Increases if q 3 is of the same sign as q 1 and decreases if q 3, is of opposite sign, , (a), , A body can be negatively charged by, [CPMT 1979], , (b) Removing some electrons from it, , A charge q 1 exerts some force on a second charge q 2 . If third, (a) Decreases, (b) Increases, (c) Remains unchanged, , 6., , (c) Along the diagonal BD, , (a) Giving excess of electrons to it, , charge q 3 is brought near, the force of q 1 exerted on q 2, , 5., , (b) Along the diagonal AC, , (d) Inversely proportional to the charge and the surface area, , (d) Four times, , (a) 1 : 5, (c) 5 : 1, 4., , (a) Zero, , 9., In the absence of other conductors, the surface charge density, The law, governing the force between electric charges is known as[CPMT 1972; MP PMT 2004], (a) Is proportional to the charge on the conductor and its surface, (a) Ampere's law, (b) Ohm's law, area, (c) Faraday's law, (d) Coulomb's law, (b) Inversely proportional to the charge and directly proportional, to the surface area, When the distance between the charged particles is halved, the force, between them becomes, [MNR 1986], (c) Directly proportional to the charge and inversely proportional, to the surface area, (a) One-fourth, (b) Half, (c) Double, , 3., , (d) Some other forces like Vander Waals, 13., , (b) K : 1, , 8., , (c) 1 : K, (d) K 2 : 1, A soap bubble is given a negative charge, then its radius, [MNR 1988; CPMT 1997; RPMT 1997;, DCE 2000; BVP 2003], (a) Decreases, (b) Increases, (c) Remains unchanged, (d) Nothing can be predicted as information is insufficient, , A total charge Q is broken in two parts Q 1 and Q 2 and they are, 1998] R from each other. The maximum force of, placed [MNR, at a distance, repulsion between them will occur, when, [MP PET 1990], , 2, , 7., , 1, , Four charges are arranged at the corners of a square ABCD , as, shown in the adjoining figure. The force on the charge kept at the, centre O is, [NCERT 1983; BHU 1999], A, +q, , B, +2q, , 14., , (a), , Q2 , , Q, Q, , Q1  Q , R, R, , (b) Q 2 , , Q, 2Q, , Q1  Q , 4, 3, , (c), , Q2 , , Q, 3Q, , Q1 , 4, 4, , (d) Q1 , , Q, Q, , Q2 , 2, 2, , Three charges 4 q, Q and q are in a straight line in the position of, 0, l / 2 and l respectively. The resultant force on q will be zero, if, Q, , [CPMT 1980], , (a) – q, (c), , , , q, 2, , (b), ,  2q, , (d), , 4q, , O, – 2q, D, , +q, C, , In O.P public school campus near Andhra Bank Old mangal bazar Sahjanwa Gorakhpur, Contact-9936998882,9453081912

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2 Electrostatics, 15., , An isolated solid metallic sphere is given Q charge. The charge, will be distributed on the sphere [MP PET 1987], (a) Uniformly but only on surface, 23., , (b) Only on surface but non-uniformly, , insulating threads of length L from a hook. This arrangement is, taken in space where there is no gravitational effect, then the angle, between the two suspensions and the tension in each will be [IIT 1986], 2, , 1, Q, 4 0 (2 L) 2, , 90 o ,, , 1 Q, 4 0 L2, , 2, , (c), 17., , 18., , 19., , 180 o ,, , 1 Q, 4 0 2 L2, , 2, , (d) 180 o ,, , 1 Q, 4 0 L2, , 25., , 9  10 3 Newton, , (a), , 9  10 3 Newton, , (b), , (c), , 1.1  10 4 Newton, , (d) 10 4 Newton, , 26., , (d), , ABC is a right angled triangle in which AB  3 cm and, , (a), , 125 dynes, , (b), , (c), , 25 dynes, , (d) Zero, , 35 dynes, , With the rise in temperature, the dielectric constant K of a liquid, (a) Increases, , (b) Decreases, , (c) Remains unchanged, , (d) Charges erratically, , Two charges q 1 and q 2 are placed in vacuum at a distance d and, , (a), , 4F, , (b), , 2F, , (c), , F, 2, , (d), , F, 4, , Force of attraction between two point charges Q and – Q, separated by d metre is Fe . When these charges are placed on, , [CPMT 1979; Kerala PMT 2002], , [AIIMS 1995], , (a), , 4 N (Attractive), , (b), , (c), , 8 N (Repulsive), , (d) Zero, , two identical spheres of radius R  0.3 d whose centres are, d metre apart, the force of attraction between them is, , 4 N (Repulsive), , Dielectric constant of pure water is 81. Its permittivity will be, , (a), , 7.12  10 10 MKS units (b), , (c), , 1.02  10 13 MKS units, , 27., , 8.86  10 12 MKS units, , (d) Cannot be calculated, , There are two metallic spheres of same radii but one is solid and the, other is hollow, then, [KCET 1994; BHU 1999], , (a) Greater than Fe, , (b) Equal to Fe, , (c) Less than Fe, , (d) Less than Fe, , When 10 14 electrons are removed from a neutral metal sphere, the, charge on the sphere becomes, [Manipal MEE 1995], , 28., , (a), , 16  C, , (b), , 16  C, , (c), , 32  C, , (d), , 32  C, , A force F acts between sodium and chlorine ions of salt (sodium, chloride) when put 1 cm apart in air. The permittivity of air and, dielectric constant of water are  0 and K respectively. When a, piece of salt is put in water electrical force acting between sodium, and chlorine ions 1 cm apart is, [MP PET 1995], , (b) Hollow sphere can be given more charge, (c) They can be charged equally (maximum), (d) None of the above, In general, metallic ropes are suspended on the carriers which take, inflammable material. The reason is, , (a), , F, K, , (b), , (c), , F, K 0, , (d), , (a) There speed is controlled, (b) To keep the centre of gravity of the carrier nearer to the earth, (c) To keep the body of the carrier in contact with the earth, 29., , (d) Nothing should be placed under the carrier, 22., , 2, , 2C and 6 C two charges are repelling each other with a force, of 12 N . If each charge is given 2C of charge, then the value of, the force will be, , (a) Solid sphere can be given more charge, , 21., , 1/ 2, , the force acting between them is F . If a medium of dielectric, constant 4 is introduced around them, the force now will be, , Two charges each of 1 coulomb are at a distance 1 km apart, the, force between them is, [CPMT 1977; DPMT 1999], , [CPMT 1984], , 20., , 24., , 2, , (b), , (c), , force acting on B is, , Two small spheres each having the charge Q are suspended by, , 180 o ,, , (b) 2, , and 20 e.s.u. are placed respectively on A , B and C . The, , (d) Non-uniformly inside the volume, , (a), , 1/2, , BC  4 cm . And  ABC = /2. The three charges 15,  12, , (c) Uniformly inside the volume, , 16., , (a), , Three equal charges are placed on the three corners of a square. If, the force between q 1 and q 2 is F12 and that between q 1 and q 3, is F13 , the ratio of magnitudes, , 0, F 0, K, , A conductor has 14.4  10 19 coulombs positive charge. The, conductor has, (Charge on electron  1.6  10 19 coulombs ), , F12, is, F13, [MP PET 1993], , FK, , 30., , (a) 9 electrons in excess, , (b) 27 electrons in short, , (c) 27 electrons in excess, , (d) 9 electrons in short, , The value of electric permittivity of free space is, , In O.P public school campus near Andhra Bank Old mangal bazar Sahjanwa Gorakhpur, Contact-9936998882,9453081912

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RADIATION INSTITUTE, for JEE (Main & Adv.)/NEET, FOUNDATION, PRE-FOUNDATION with Board,, [MP PET 1996; RPET 2001], , 31., , (a), , 9  10 9 NC 2 / m 2, , (b), , 8.85  10 12 Nm 2 / C 2 sec, , (c), , 8.85  10 12 C 2 / Nm 2, , (d), , 9  10 9 C 2 / Nm 2, , 37., , charge is moved towards the other by 0.01 m , then the force, between them will become, [SCRA 1994], , Two similar spheres having  q and  q charge are kept at a, certain distance. F force acts between the two. If in the middle of, two spheres, another similar sphere having  q charge is kept, then, it experience a force in magnitude and direction as, , 38., , (a) Zero having no direction, , 32., , 33., , (b), , 8 F towards  q charge, , (c), , 8 F towards  q charge, , (d), , 4 F towards  q charge, , 39., , A charge Q is divided into two parts of q and Q  q . If the, coulomb repulsion between them when they are separated is to be, Q, maximum, the ratio of, should be [MP PET 1997], q, (a) 2, , (b) 1 / 2, , (c) 4, , (d) 1 / 4, , 40., , Number of electrons in one coulomb of charge will be, [MP PMT/PET 1998; Pb. PMT 1999;, AIIMS 1999; RPET 2001], , 34., , 35., , 36., , (a), , 5.46  10 29, , (b), , 6.25  10 18, , (c), , 1.6  10 19, , (d), , 9  10 11, , When air is replaced by a dielectric medium of constant k , the, maximum force of attraction between two charges separated by a, distance, [CBSE PMT 1999], (a) Decreases k times, , (b) Remains unchanged, , (c) Increases k times, , (d) Increases k 1 times, , A glass rod rubbed with silk is used to charge a gold leaf, electroscope and the leaves are observed to diverge. The, electroscope thus charged is exposed to X-rays for a short period., Then, [AMU 1995], (a) The divergence of leaves will not be affected, (b) The leaves will diverge further, (c) The leaves will collapse, (d) The leaves will melt, One metallic sphere A is given positive charge whereas another, identical metallic sphere B of exactly same mass as of A is given, equal amount of negative charge. Then, [AMU 1995; RPET 2000; CPMT 2000], , 41., , 42., , 7.20 N, , (b) 11.25 N, , (c), , 22.50 N, , (d), , 43., , 45.00 N, , Two charged spheres separated at a distance d exert a force F on, each other., they, are immersed in a liquid of dielectric constant 2,, [MP IfPET, 1996], then what is the force (if all conditions are same), (a), , F, 2, , (b), , F, , (c), , 2F, , (d), , 4F, , (a), , 10 N, , (b), , 10 N, , (c), , 20 N, , (d), , 20 N, , When 10 19 electrons are removed from a neutral metal plate, the, electric charge on it is, [Karnataka CET (Engg./Med.) 1999], (a) – 1.6 C, (b) + 1.6 C, (c) 10 C, (d) 10 C, –19, , Electric charges of 1C,  1C and 2 C are placed in air at the, corners A, B and C respectively of an equilateral triangle ABC having, length of each side 10 cm. The resultant force on the charge at C is[EAMCET (, (a) 0.9 N, , (b) 1.8 N, , (c) 2.7 N, , (d) 3.6 N, , Charge on  -particle is, 4.8  10, , 19, , C, , [MH CET 2000], (b) 1.6  10, , 19, , C, , (c) 3.2  10 19 C, (d) 6.4  10 19 C, Two small conducting spheres of equal radius have charges, 10 C and 20 C respectively and placed at a distance R, from each other experience force F1 . If they are brought in contact, and separated to the same distance, they experience force F2 . The, ratio of F1 to F2 is, [MP PMT 2001], (a) 1 : 8, (c) 1 : 2, , 44., , 45., , [, , Two point charges 3 C and 8 C repel each other with a, force of 40 N . If a charge of 5 C is added to each of them, then, the force between them will become, [SCRA 1998; JIPMER 2000], , (a), , (b) Mass of A increases, (d) Mass of B increases, , (a), , +19, , (a) Mass of A and mass of B still remain equal, (c) Mass of B decreases, , Electrostatics 3, The force between two charges 0.06 m apart is 5 N . If each, , (b) – 8 : 1, (d) – 2 : 1, , Two charges each equal to 2 C are 0.5m apart. If both of them, exist inside vacuum, then the force between them is, [CPMT 2001], (a) 1.89 N, (b) 2.44 N, (c) 0.144 N, (d) 3.144 N, Two charges are at a distance ‘d’ apart. If a copper plate (conducting, d, medium) of thickness, is placed between them, the effective force, 2, will be, [UPSEAT 2001; J & K CET 2005], , In O.P public school campus near Andhra Bank Old mangal bazar Sahjanwa Gorakhpur, Contact-9936998882,9453081912

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4 Electrostatics, (a) 2F, 46., , (b), , 2.0  10 10 N, , (b), , (c), , , , Q, , ,, , Q, , 50., , 51., , 3q 2, 4 0 L2, 1, , (b), , q2, 4 0 L2, , (d), , 1 q2, 12 0 L2, , (a), (b), , 58., ,  Q /(4 0 a ), , 52., , e2, rˆ, r3, , (b), , K, , (c), , K, , e2 , r, r3, , (d), , K, , +Q, , Two particle of equal mass m and, B chargea q areCplaced at a, distance of 16 cm. They do not experience any force. The value of, q, is, [MP PET 2003], m, , e2, r2, , rˆ, , 8  10 5, , (b) 80  10 17, , (c) 5  10 14, (d) 1.28  10 17, Two point charges placed at a certain distance r in air exert a force, F on each other. Then the distance r' at which these charges will, exert the same force in a medium of dielectric constant k is given by, [EAMCET 1990; MP PMT 2001], (a) r, (b) r/k, , r/ k, , (d) r k, , Dielectric constant for metal is, [MP PMT/PET 1998], (a) Zero, (b) Infinite, (c) 1, (d) Greater than 1, A charge of Q coulomb is placed on a solid piece of metal of, irregular shape. The charge will distribute itself, , (b) Uniformly on the surface of the object, (c) Such that the potential energy of the system is minimised, (d) Such that the total heat loss is minimised, 59., , 60., , Q 2 /(2 0 a 2 ), , e2 , r, r3, , A body has – 80 micro coulomb of charge. Number of additional, electrons in it will be, [MP PMT 2003], , Five balls numbered 1 to 5 are suspended using separate threads., Pairs (1, 2), (2, 4) and (4, 1) show electrostatic attraction, while pair, (2, 3) and (4, 5) show repulsion. Therefore ball 1 must be [NCERT 1980; MP PM, [AIIMS 2003], (a) Positively charged, (b) Negatively charged, (c) Neutral, , +Q, , –Q, , K, , (a) Uniformly in the metal object, , A, 2, , 4 0 G, , [MP PMT 1991], , Q 2 /(4 0 a 2 ), , , (d), , G, , (a), , (c), 57., , 1, , (c) Zero, (d), , 55., , 56., , Two charges placed in air repel each other by a force of 10 4 N ., When oil is introduced between the charges, the force becomes, 2.5  10 5 N . The dielectric constant of oil is, [MP PET 2003], (a) 2.5, (b) 0.25, (c) 2.0, (d) 4.0, Three charges are placed at the vertices of an equilateral triangle of, side ‘a’ as shown in the following figure. The force experienced by, the charge placed at the vertex A in a direction normal to BC is, ,  0, , circular orbit of radius r. The coulomb force F between the two is, 1, (Where K , ), [CBSE PMT 2003], 4 0, , b, c, , G, 4 0, , (b), , When a glass rod is rubbed with silk, it, [MP PET 2003], (a) Gains electrons from silk (b) Gives electrons to silk, (c) Gains protons from silk, (d) Gives protons to silk, An electron is moving round the nucleus of a hydrogen atom in a, , (a), , 4c 2, (d) None of the above, Three charges each of magnitude q are placed at the corners of an, equilateral triangle, the electrostatic force on the charge placed at, the center is (each side of triangle is L), [DPMT 2002], , (c), , 54., , a, , Q, , (a) Zero, , 53., , 2.0  10 4 N, , 4b 2 4c 2, , 0,, , (c), , 4.6  10 8 N, , (c) 2.0  10 8 N, (d) 2.0  10 6 N, A solid conducting sphere of radius a has a net positive charge 2Q., A conducting spherical shell of inner radius b and outer radius c is, concentric with the solid sphere and has a net charge – Q. The, surface charge density on the inner and outer surfaces of the, spherical shell will be, [AMU 2002], 2Q, Q, (a) , ,, 4b 2 4c 2, (b), , 49., , 2.3  10 8 N, , (c) 1.5  10 8 N, (d) None of these, Two copper balls, each weighing 10g are kept in air 10 cm apart. If, one electron from every 10 6 atoms is transferred from one ball to, the other, the coulomb force between them is (atomic weight of, copper is 63.5), [KCET 2002], (a), , 48., , (a) l, , (c) 0, (d), 2F, Two electrons are separated by a distance of 1Å. What is the, coulomb force between them, [MH CET 2002], (a), , 47., , (b) F / 2, , (d) Made of metal, , Equal charges q are placed at the four corners A, B, C, D of a, square of length a . The magnitude of the force on the charge at B, will be, [MP PMT 1994; DPMT 2001], (a), , (c), , 3q 2, 4 0 a 2, 1  2 2  q2, , , ,  4 a 2, 2, 0, , , , (b), , 4q 2, 4 0 a 2, , , 1  q 2, (d)  2 , 2, 2  4 0 a, , , In O.P public school campus near Andhra Bank Old mangal bazar Sahjanwa Gorakhpur, Contact-9936998882,9453081912

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RADIATION INSTITUTE, for JEE (Main & Adv.)/NEET, FOUNDATION, PRE-FOUNDATION with Board,, 61., , 62., , 63., , 64., , Two identical conductors of copper and aluminium are placed in an, identical electric fields. The magnitude of induced charge in the, aluminium will be, [AIIMS 1999], (a) Zero, , (b) Greater than in copper, , (c) Equal to that in copper, , (d) Less than in copper, , Two spherical conductors B and C having equal radii and carrying, equal charges in them repel each other with a force F when kept, apart at some distance. A third spherical conductor having same, radius as that of B but uncharged is brought in contact with B, then, brought in contact with C and finally removed away from both. The, new force of repulsion between B and C is, , 69., , 70., , (b) 12000 N, , (c) 24000 N, , (d) 36000 N, , The number of electrons in 1.6 C charge will be, , (a), , (d) 1.1  10, 1.1  1019, [AIEEE 2004], Four metal conductors having different shapes, , 71., , 2, , F/4, , (b), , 3F / 4, , 1., , A sphere, , 2., , Cylindrical, , (c), , F/8, , (d), , 3F / 8, , 3., , Pear, , 3., , Lightning conductor, , are mounted on insulating stands and charged. The one which is, best suited to retain the charges for a longer time is, , When a body is earth connected, electrons from the earth flow into, the body. This means the body is….. [KCET 2004], (a) Unchanged, , (b) Charged positively, , (c) Charged negatively, , (d) An insulator, , [KCET 2005], (a) 1, , The charges on two sphere are +7C and – 5C respectively. They, experience a force F. If each of them is given and additional charge of, – 2C, the new force of attraction will be, (a) F, , (b) F / 2, , (c), , (d) 2F, , F/ 3, , 72., , The ratio of electrostatic and gravitational forces acting between, –19, , 11, , m, will be, , 1., , –31, , of proton = 1.6  10 27 kg , G  6.7  10 11 Nm 2 / kg 2 ), (a) 2.36  10, , 39, , (b) 2.36  10, , (c) 2.34  10, , 41, , (d) 2.34  10, , 40, , 42, , Two point charges 3  10 C and 8  10 C repel each other by a, force of 6  10 N. If each of them is given an additional charge – 6,  10 C, the force between them will be, –6, , Electric Field and Potential, A charge q is placed at the centre of the line joining two equal, charges Q. The system of the three charges will be in equilibrium, if, q is equal to, [RPET 1997; Pb PMT 2003], [IIT 1987; CBSE PMT 1995; Bihar MEE 1995; CPMT 1999;, MP PET 1999; MP PMT 1999, 2000; RPET 1999;, KCET 2001; AIEEE 2002; AFMC 2002;, Kerala PMT 2004; J & K CET 2004], (a), , 6, , (a) 2.4  10 N (attractive), , (b) 2.4  10 N (attractive), , (c) 1.5  10 N (repulsive), , (d) 1.5  10 N (attractive), , –3, , –3, , (b) 2, , (c) 3, (d) 4, Identify the wrong statement in the following. Coulomb's law, correctly describes the electric force that, [KCET 2005], (a) Binds the electrons of an atom to its nucleus, (b) Binds the protons and neutrons in the nucleus of an atom, (c) Binds atoms together to form molecules, (d) Binds atoms and molecules together to form solids, , –6, , –3, , 68., , (b) 10, , 20, , (c), , (Charge on electron = 1.6  10 C, mass of electron = 9.1  10 kg, mass, , 67., , 10, , 19, , (a), , electron and proton separated by a distance 5  10, , 66., , (a) 9000 N, , [RPET 2004], , [RPET 2002], , 65., , Electrostatics 5, An infinite number of charges, each of charge 1 C, are placed on, the x-axis with co-ordinates x = 1, 2, 4, 8, ..... If a charge of 1 C is, kept at the origin, then what is the net force acting on 1 C charge, , (c), , –9, , –3, , Two equally charged, identical metal spheres A and B repel each, other with a force 'F'. The spheres are kept fixed with a distance 'r', between them. A third identical, but uncharged sphere C is brought, in contact with A and then placed at the mid-point of the line, joining A and B. The magnitude of the net electric force on C is, (a) F, , (b) 3F/4, , (c) F/2, , (d) F/4, , Two charges of equal magnitudes and at a distance r exert a force F, on each other. If the charges are halved and distance between them, is doubled, then the new force acting on each charge is, (a) F / 8, , (b) F / 4, , (c) 4 F, , (d) F / 16, , Q, 2, [DPMT 2003], Q, , 4, , , (b), , , , Q, 4, , (d), , , , Q, 2, , 2., , Inside a hollow charged spherical conductor, the potential, [CPMT 1971; MP PMT 1986; RPMT 1997], (a) Is constant, (b) Varies directly as the distance from the centre, (c) Varies inversely as the distance from the centre, [UPSEAT 2004; DCE 2005], (d) Varies inversely as the square of the distance from the centre, 3., Two small spheres each carrying a charge q are placed r metre, apart. If one of the spheres is taken around the other one in a, circular path of radius r , the work done will be equal to[CPMT 1975, 91, 2001;, EAMCET 1994; MP PET 1995; MNR 1998; Pb. PMT 2000], [DCE, 2004] them  r, (a) Force, between, (b) Force between them  2r, , In O.P public school campus near Andhra Bank Old mangal bazar Sahjanwa Gorakhpur, Contact-9936998882,9453081912

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6 Electrostatics, , 4., , (c) Force between them / 2r, (d) Zero, The electric charge in uniform motion produces, , 11., , [CPMT 1971], , 5., , 6., , (a) An electric field only, (b) A magnetic field only, (c) Both electric and magnetic field, (d) Neither electric nor magnetic field, Two charged spheres of radii 10 cm and 15 cm are connected by a, thin wire. No current will flow, if they have, [MP PET 1991; CPMT 1975], (a) The same charge on each, (b) The same potential, (c) The same energy, (d) The same field on their surfaces, The electric field inside a spherical shell of uniform surface charge, density is, [CPMT 1982; MP PET 1994; RPET 2000], , 12., , 150 2 volt, , (b) 1500 2 volt, , (c), , 900 2 volt, , (d) 900 volt, , A uniform electric field having a magnitude E 0 and direction along, , [MP PMT 1987], , 13., , (b) Constant, less than zero, (c) Directly proportional to the distance from the centre, (d) None of the above, The electric potential V at any point O (x, y, z all in metres) in, space is given by V  4 x 2 volt . The electric field at the point, , (a), , the positive X  axis exists. If the potential V is zero at x  0 ,, then its value at X   x will be, , (a) Zero, , 7., , 10,  10 9 C are placed at each of the four corners, 3, of a square of side 8 cm . The potential at the intersection of the, diagonals is, [BIT 1993], , Charges of , , 14., , (1m, 0, 2m) in volt / metre is, , (a), , V( x )   xE 0, , (b), , Vx   xE 0, , (c), , Vx   x 2 E 0, , (d), , Vx   x 2 E 0, , Three charges 2q,  q,  q are located at the vertices of an, equilateral triangle. At the centre of the triangle, [MP PET 1985; J & K CET 2004], (a) The field is zero but potential is non-zero, (b) The field is non-zero but potential is zero, (c) Both field and potential are zero, (d) Both field and potential are non-zero, Figure shows the electric lines of force emerging from a charged, body. If the electric field at A and B are E A and E B respectively, and if the displacement between A and B is r then, , [IIT 1992; RPET 1999; MP PMT 2001], (a) 8 along negative X  axis, (b) 8 along positive X  axis, , A, , (c) 16 along negative X  axis, , B, , r, , (d) 16 along positive Z  axis, 8., , A hollow metal sphere of radius 5 cm is charged so that the, potential on its surface is 10 V. The potential at the centre of the, sphere is, , (a), , [IIT 1983; MNR 1990; MP PET/PMT 2000; DPMT 2004], (a) 0 V, , 15., , [CPMT 1985; AIEEE 2002], , If a unit positive charge is taken from one point to another over an, equipotential surface, then, , (a), , 1 q, 4 0 r 2, , (b), , 1 q, 4 0 r, , [KCET 1994; CPMT 1997; CBSE PMT 2000], (a) Work is done on the charge, (b) Work is done by the charge, (d) No work is done, Electric lines of force about negative point charge are, [MP PMT 1987], (a) Circular, anticlockwise, (b) Circular, clockwise, (c) Radial, inward, (d) Radial, outward, , +q, A, , r, , (c) Zero, , (c) Work done is constant, 10., , EA , , corner. The electric intensity at O will be, , (d) Same as at point 25 cm away from the surface, 9., , E A  EB, , (b), , EB, E, (d) E A  2B, r, r, ABC is an equilateral triangle. Charges  q are placed at each, (c), , (b) 10 V, , (c) Same as at point 5 cm away from the surface, , E A  EB, , (d), 16., , 1 3q, 4 0 r 2, , r, , r, , O, , +q, , +q, C, , B, , In the electric field of a point charge q , a certain charge is carried, from point A to B , C , D and E . Then the work done, A, , (a) Is least along the path AB, (b) Is least along the path AD, +q, , E, , B, C, , D, , In O.P public school campus near Andhra Bank Old mangal bazar Sahjanwa Gorakhpur, Contact-9936998882,9453081912

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RADIATION INSTITUTE, for JEE (Main & Adv.)/NEET, FOUNDATION, PRE-FOUNDATION with Board,, Electrostatics 7, (b) Along a line of force, if its initial velocity is zero, (c) Along a line of force, if it has some initial velocity in the, direction of an acute angle with the line of force, (d) None of the above, , (c) Is zero along all the paths AB, AC, AD and AE, (d) Is least along AE, 17., , The magnitude of electric field intensity E is such that, an electron, placed in it would experience an electrical force equal to its weight, is given by, [CPMT 1975, 80; AFMC 2001; BCECE 2003], (a), (c), , 18., , (b), , mge, e, mg, , (d), , mg, e, , e, , 2, , m2, , 26., , g, , 20., , If E is the electric field intensity of an electrostatic field, then the, electrostatic energy density is proportional to, [MP PMT 2003], (a), , E, , (b), , E2, , (c), , 1 / E2, , (d), , E3, , A metallic sphere has a charge of 10 C . A unit negative charge is, brought from A to B both 100 cm away from the sphere but A, , A conductor with a positive charge, (a) Is always at  ve potential, , being east of it while B being on west. The net work done is, (a) Zero, , (b) Is always at zero potential, (c) Is always at negative potential, (d) May be at  ve , zero or ve potential, 19., , 25., , (c), , An electron and a proton are in a uniform electric field, the ratio of, their accelerations will be, [NCERT 1984; MP PET 2002], (a) Zero, (b) Unity, (c) The ratio of the masses of proton and electron, (d) The ratio of the masses of electron and proton, Two parallel plates have equal and opposite charge. When the space, between them is evacuated, the electric field between the plates is, 2  10 5 V / m . When the space is filled with dielectric, the electric, , 27., , 28., , 2 / 10 joule, , 2 / 10 joule, , (d), , 1 / 10 joule, , Two charges 4 e and e are at a distance x apart. At what, distance, a charge q must be placed from charge e so that it is in, equilibrium, (a), , x/2, , (b), , 2x / 3, , (c), , x /3, , (d), , x /6, , An uncharged sphere of metal is placed in between two charged, plates as shown. The lines of force look like, [MP PMT 1985; KCET 2004], , field becomes 1  10 5 V / m . The dielectric constant of the dielectric, material, [MP PET 1989], (a) 1/2, (b) 1, (c) 2, (d) 3, 21., , (b), , The insulation property of air breaks down at E  3  10 6, volt/metre. The maximum charge that can be given to a sphere of, diameter 5 m is approximately (in coulombs), , + + + + + + +, , + + + + + + +, , – – – – – – –, A, + + + + + + +, , – – – – – – –, B, + + + + + + +, , – – – – – – –, C, , – – – – – – –, D, , [MP PMT 1990], (a), (c), 22., , 2  10, , 2, , 2  10, , 4, , 3, , (b), , 2  10, , (d), , 2  10 5, , The distance between the two charges 25 C and 36 C is, 11cm At what point on the line joining the two, the intensity will, be zero, (a) At a distance of 5 cm from 25 C, , 29., , 24., , A, , (b), , B, , (c), , C, , (d), , D, , The intensity of electric field required to balance a proton of mass, , 1.7  10 27 kg and charge 1.6  10 19 C is nearly, , (b) At a distance of 5 cm from 36 C, , 23., , (a), , (c) At a distance of 10 cm from 25 C, , (a), , 1  10 7 V / m, , (b) 1  10 5 V / m, , (d) At a distance of 11 cm from 36 C, , (c), , 1  10 7 V / m, , (d) 1  10 5 V / m, , Two spheres A and B of radius 4 cm and 6 cm are given, charges of 80 c and 40 c respectively. If they are connected by, a fine wire, the amount of charge flowing from one to the other is, (a), , 20 C from A to B, , (b) 16 C from A to B, , (c), , 32 C from B to A, , (d), , 32 C from A to B, , A charge particle is free to move in an electric field. It will travel, (a) Always along a line of force, , 30., , On rotating a point charge having a charge q around a charge Q in, a circle of radius r. The work done will be, [MP PET 1991] [CPMT 1990, 97; MP PET 1993; AIIMS 1997;, DCE 2003; KCET 2005], (a), , q  2r, [IIT 1979], , (b), , q  2Q, r, , In O.P public school campus near Andhra Bank Old mangal bazar Sahjanwa Gorakhpur, Contact-9936998882,9453081912

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8 Electrostatics, (c) Zero, 31., , (d), , 38., , Q, 2 0 r, , making an angle 60 with the X-axis is 4.0, what is the value of E, , Two point charges Q and – 3Q are placed at some distance apart., , (a), , If the electric field at the location of Q is E then at the locality of, 3 Q , it is, , 32., , 33., , 34., , (c), , [BIT 1987], , (a), , E, , (b), , E/3, , (c), , 3 E, , (d), , E / 3, , 39., , The number of electrons to be put on a spherical conductor of, radius 0 .1 m to produce an electric field of 0.036 N / C just above, its surface is, [MNR 1994; KCET (Engg.) 1999;, MH CET (Med.) 2001], (a), , 2.7  10 5, , (b), , 2.6  10 5, , (c), , 2.5  10 5, , (d), , 2.4  10 5, , 20 N / C, , (b), , 500 N / C, , (c), , 5 N /C, , (d), , 250 N / C, , The intensity of the electric field required to keep a water drop of, radius 10 5 cm just suspended in air when charged with one, electron is approximately, [MP PMT 1994], (a), , 260 volt / cm, , (b), , (c), , 130 volt / cm, , (d) 130 newton / coulomb, , 40., , 41., , Conduction electrons are almost uniformly distributed within a, , 36., , 42., , 43., , (b), , 2Q 2,  0 a, , (d), , 2Q 2, 4  0 a, Q2, 2 0 a, , 2 :1, 1:4, , [BHU 1995; MNR 1991; UPSEAT 2000; Pb PET 2004], (b) 1 : 2, (d) 4 : 1, , Deutron and   particle are put 1 Å apart in air. Magnitude of, intensity of electric field due to deutron at   particle is, (a) Zero, (b), , 2.88  10 11 newton / coulomb, , (c), , 1.44  10 11 newton / coulomb, , Angle between equipotential surface and lines of force is, [MP PET 1995], (a) Zero, (b) 180, (c) 90, (d) 45, Below figures (1) and (2) represent lines of force. Which is correct, statement, [MP PET 1995], , Three particles, each having a charge of 10 C are placed at the, corners of an equilateral triangle of side 10 cm . The electrostatic, potential, energy, of, the, system, is, (Given, 1, 9, 2, 2, [MP PMT 1994],  9  10 N  m / C ), 4 0, (a) Zero, (c) 27 J, , 37., , (d) None of these, , (d) 5.76  10 11 newton / coulomb, , (b) Depends upon E, (c) Depends upon E, (d) Depends upon the atomic number of the conducting element, , 4 N /C, , A particle A has charge q and a particle B has charge  4 q, with each of them having the same mass m . When allowed to fall, from rest through the same electric potential difference, the ratio of, v A 1994; DPMT 2002], [MP PET, their speed, will become, vB, (a), (c), , 260 newton / coulomb, , conducting plate. When placed in an electrostatic field E , the, electric field within the plate, [MP PMT 1994], (a) Is zero, , 5 N /C, , (b), , Four equal charges Q are placed at the four corners of a square of, each side is ' a' . Work done in removing a charge – Q from its, centre to infinity is, [AIIMS 1995], , (c), , (g  10 newton / kg , e  1.6  10 19 coulomb), , 35., , 3 N /C, , (a) 0, , Two plates are 2 cm apart, a potential difference of 10 volt is, applied between them, the electric field between the plates is, (a), , There is an electric field E in X-direction. If the work done on, moving a charge 0 .2 C through a distance of 2 m along a line, , (b) Infinite, (d) 100 J, , The electric field near a conducting surface having a uniform surface, charge density  is given by, [MP PMT 1994], (a), (b), (c), (d), , , and is parallel to the surface, 0, 2, , 0, , and is parallel to the surface, , , and is normal to the surface, 0, 2, , 0, , and is normal to the surface, , 44., , 45., , (2), (1), (a) Figure (1) represents magnetic lines of force, (b) Figure (2) represents magnetic lines of force, (c) Figure (1) represents electric lines of force, (d) Both figure (1) and figure (2) represent magnetic lines of force, The unit of electric field is not equivalent to, [MP PMT 1995], (a), , N /C, , (b), , J /C, , (c), , V /m, , (d), , J /C m, , A flat circular disc has a charge Q uniformly distributed on the, disc. A charge q is thrown with kinetic energy E towards the, disc along its normal axis. The charge q will, [MP PMT 1995], (a) Hit the disc at the centre, (b) Return back along its path after touching the disc, (c) Return back along its path without touching the disc, , In O.P public school campus near Andhra Bank Old mangal bazar Sahjanwa Gorakhpur, Contact-9936998882,9453081912

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RADIATION INSTITUTE, for JEE (Main & Adv.)/NEET, FOUNDATION, PRE-FOUNDATION with Board,, , 46., , 47., , Electrostatics 9, (d) Any of the above three situations is possible depending on the, 53., In the figure the charge Q is at the centre of the circle. Work done, magnitude of E, is maximum when another charge is taken from point P to, At a certain distance from a point charge the electric field is, 500 V / m and the potential is 3000 V . What is this distance[MP PMT 1995; Pb. PMT 2001; AFMC 2001], P, (a), , 6m, , (b) 12 m, , (c), , 36 m, , (d) 144 m, , The magnitude of electric field E in the annular region of a, charged cylindrical capacitor, [IIT 1996], (a) Is same throughout, (b) Is higher near the outer cylinder than near the inner cylinder, , 54., , 49., , 50., , (b), , L, , (c), , M, , (d), , N, , (c), 55., , 44 m / s, , (d), , 40 m / s, , Four identical charges  50 C each are placed, one at each corner, , 1, , 2, , 2, , of a square of side 2 m . How much external energy is required to, , 3, , 3, , 4, , 4, , bring another charge of  50 C from infinity to the centre of the, square, , (a), , 2.304  10 10 N / C, , (b) 14.4 V / m, , (c), , 16 V / m, , (d) 1.44  10 11 N / C, , 2 , ,  Given 1  9  10 9 Nm , 2 , , 4 0, C , , , 56., , What is the magnitude of a point charge due to which the electric, field 30 cm away has the magnitude 2 newton / coulomb, , [MP PMT 1996], 2  10 11 coulomb, , (b), , 3  10 11 coulomb, , 57., , (c) 5  10 11 coulomb, (d) 9  10 11 coulomb, Two charge  q and  q are situated at a certain distance. At the, point exactly midway between them, (a) Electric field and potential both are zero, (b) Electric field is zero but potential is not zero, (c) Electric field is not zero but potential is zero, , (a), , 64 J, , (b), , (c), , 16 J, , (d) 10 J, , 58., , 41 J, , In Millikan's oil drop experiment an oil drop carrying a charge Q is, held stationary by a potential difference 2400 V between the, plates. To keep a drop of half the radius stationary the potential, difference had to be made 600 V . What is the charge on the, second drop, [MP PET 1997], (a), , Q, 4, , (b), , Q, 2, , (c), , Q, , (d), , 3Q, 2, , A charge of 5 C experiences a force of 5000 N when it is kept in, a uniform electric field. What is the potential difference between two, points separated by a distance of 1 cm, (a), , 10 V, , (b), , 250 V, , (c), , 1000 V, , (d), , 2500 V, , Two insulated charged conducting spheres of radii 20 cm and, , Two positive charges of 20 coulomb and Q coulomb are, , 15 cm respectively and having an equal charge of 10 C are, connected by a copper wire and then they are separated. Then, (a) Both the spheres will have the same charge of 10 C, , situated at a distance of 60 cm . The neutral point between them is, , (b) Surface charge density on the 20 cm sphere will be greater, , (d) Neither electric field nor potential is zero, 52., , M, , A mass m  20 g has a charge q  3.0 mCN. It moves with a, , [1 / 4 0  9  10 9 Nm 2 / C 2 ], , 51., , Q, , 1, , (a) 1, (b) 2, (c) 3, (d) 4, The distance between a proton and electron both having a charge, 1.6  10 19 coulomb , of a hydrogen atom is 10 10 metre . The, value of intensity of electric field produced on electron due to, proton will be, [MP PET 1996], , (a), , L, , 80 N / C in the same direction as the velocity of the mass. The, velocity of the mass after 3 seconds in this region is, (a) 80 m / s, (b) 56 m / s, , (d) Varies as 1 / r 2 , where r is the distance from the axis, A metallic solid sphere is placed in a uniform electric field. The lines, of force follow the path(s) shown in figure as, [IIT 1996], , K, , velocity of 20 m / s and enters a region of electric field of, , (c) Varies as 1 / r , where r is the distance from the axis, 48., , K, , (a), , at a distance of 20 cm from the 20 coulomb charge. Charge Q, is, (a), (c), , 30 C, , 60 C, , (b), (d), , 40 C, , 80 C, , than that on the 15 cm sphere, (c) Surface charge density on the 15 cm sphere will be greater, than that on the 20 cm sphere, (d) Surface charge density on the two spheres will be equal, , In O.P public school campus near Andhra Bank Old mangal bazar Sahjanwa Gorakhpur, Contact-9936998882,9453081912

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10 Electrostatics, 59., , Equal charges q are placed at the vertices A and B of an, , 66., , equilateral triangle ABC of side a . The magnitude of electric field, at the point C is, [MP PMT 1997], , q, , (a), , 4 0 a, 3q, , (c), 60., , (b), , 2, , 4  0 a, , (d), , 2, , x  1 is, , 2q, 4  0 a, , 2, , 67., , q, 2 0 a, , charge 2q is placed at the midpoint. The potential energy of the, system is, [MP PMT 1997], , 61., , (a), , 8 0 a, , (c), , , , 7q 2, 8 0 a, , (b), , 6q 2, 8 0 a, , (d), , 9q 2, 8 0 a, , [MP PET 1999], , (a), , 20 V / m, , (b) 6 V / m, , (c), , 11 V / m, , (d), , 23 V / m, , Two metal pieces having a potential difference of 800 V are, 0.02 m apart horizontally. A particle of mass 1.96  10 15 kg is, suspended in equilibrium between the plates. If e is the elementary, charge, then charge on the particle is, , 2, , Two equal charges q are placed at a distance of 2a and a third, , q2, , The electric potential V is given as a function of distance x, (metre) by V  (5 x 2  10 x  9) volt . Value of electric field at, , (a), 68., , (b), , e, , [, , 3e, , (c) 6 e, (d) 8 e, The figure shows some of the electric field lines corresponding to an, electric field. The figure suggests, [MP PMT 1999], A, , B, , C, , Two point charges 100  C and 5  C are placed at points A, and B respectively with AB  40 cm . The work done by external, force in displacing the charge 5  C from B to C , where, BC  30 cm ,, , 1, 4 0, , 62., , 63., , ABC , , angle, ,  9  10 9 Nm 2 / C 2, , (a), , 9J, , (c), , 9, J, 25, , , 2, , and, 69., , [MP PMT 1997], , (b), , 81, J, 20, , (d), , 9,  J, 4, , 70., , (a), , Newton / Coulomb, , (b), , Joule / Coulomb, , (b), , E A  E B  EC, , (c), , E A  EC  E B, , (d), , E A  EC  E B, , Two spheres of radius a and b respectively are charged and joined, by a wire. The ratio of electric field of the spheres is, (a), , a/b, , (b) b / a, , (c), , a2 / b 2, , (d) b 2 / a 2, , A particle of mass m and charge q is placed at rest in a uniform, electric field E and then released. The kinetic energy attained by, the particle after moving a distance y is, , (c), , Volt metre, , (d), , Newton / metre, , Equal charges are given to two spheres of different radii. The, potential will, [MP PMT/PET 1998; MH CET 2000], , [CBSE PMT 1998; Kerala PMT 2005], , 71., , (b) Be more on the bigger sphere, , (a), , qEy, , (c), , qEy, , 2, , (c), , (d) Depend on the nature of the materials of the spheres, An alpha particle is accelerated through a potential difference of, , 72., , 10 6 volt . Its kinetic energy will be, , (b) qE 2 y, (d) q 2 Ey, , A hollow insulated conducting sphere is given a positive charge of, 10  C . What will be the electric field at the centre of the sphere if, its radius is 2 meters, [CBSE PMT 1998], (a) Zero, , (c) Be equal on both the spheres, , 20  Cm 2, , (b) 5  Cm 2, (d) 8  Cm 2, , An electron of mass m e initially at rest moves through a certain, distance in a uniform electric field in time t 1 . A proton of mass, , m p also initially at rest takes time t 2 to move through an equal, distance in this uniform electric field. Neglecting the effect of, gravity, the ratio of t 2 / t1 is nearly equal to, , [MP PMT/PET 1998], , 65., , E A  E B  EC, , The unit of intensity of electric field is [MP PMT/PET 1998], , (a) Be more on the smaller sphere, , 64., , (a), , (a), , 1 MeV, , (b), , 2 MeV, , (c), , 4 MeV, , (d), , 8 MeV, , (a) 1, , A charge of 5 C is given a displacement of 0 .5 m . The work done, in the process is 10 J . The potential difference between the two, points will be, [MP PET 1999], (a), , 2V, , (b), , 0.25 V, , (c), , 1V, , (d), , 25 V, , (c), 73., , (m e / m p )1 / 2, , (b) (m p / m e )1 / 2, (d) 1836, , A cube of side b has a charge q at each of its vertices. The, electric field due to this charge distribution at the centre of this, cube will be, [KCET 1994, 2000], (a), , q /b2, , (b) q / 2b 2, , In O.P public school campus near Andhra Bank Old mangal bazar Sahjanwa Gorakhpur, Contact-9936998882,9453081912, , [

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RADIATION INSTITUTE, for JEE (Main & Adv.)/NEET, FOUNDATION, PRE-FOUNDATION with Board,, (c), 74., , 75., , 32q / b 2, , (d) Zero, , 1.61 N / C, , (b), , (c), , 262 N / C, , (d) 1610 N / C, , 82., , [RPET 1999], Q, , (a), , 1.02  10 7 N / C upwards, , (b), , 2.04  10 7 N / C downwards, , (c), , 2.04  10 N / C upwards, , – 2Q, , 83., , 80., , 81., , 1, 2q, ., 4 0 d 2, , (a), , 9  10 3 J, , (b) 9  10 3 eV, , (c), , 2eV / m, , (d) Zero, , An oil drop having charge 2e is kept stationary between two, parallel horizontal plates 2.0 cm apart when a potential difference of, 12000 volts is applied between them. If the density of oil is 900, kg/m , the radius of the drop will be, 3, , [AMU 1999], –Q, , A sphere of radius 1 cm has potential of 8000 V , then energy, density near its surface will be, [RPET 1999], (a), , 64  10 5 J / m 3, , (b), , 8  10 3 J / m 3, , (c), , 32 J / m 3, , (d), , 2.83 J / m 3, , 84., , (b) 1.7  10 m, , (c), , 1.4  10 6 m, , (d) 1.1  10 6 m, , The ratio of momenta of an electron and an -particle which are, accelerated from rest by a potential difference of 100 volt is, , (c), , (a), , 0 .1 m, , (b), , 0.04 m, , (c), , 0.033 m, , (d), , 0.33 m, , 85., , 86., , How much kinetic energy will be gained by an   particle in going, from a point at 70 V to another point at 50 V, [RPET 1997], (a) 40 eV, (b) 40 keV, , 87., , (c), , 88., , 40 MeV, , (d), , 0 eV, , 6, , 2.0  10 m, , (a) 1, , Point charges 4 q,  q and 4 q are kept on the x  axis at, , (a) Only q is in stable equilibrium, (b) None of the charges are in equilibrium, (c) All the charges are in unstable equilibrium, (d) All the charges are in stable equilibrium, Two point charges of 20  C and 80  C are 10 cm apart., Where will the electric field strength be zero on the line joining the, charges from 20  C charge, [RPET 1997], , 6, , (a), + 2Q, , [CBSE PMT 1992], , 79., , 11, , What is the potential energy of the equal positive point charges of, 1C each held 1 m apart in air [AMU 1999], , points x  0, x  a and x  2a respectively, then, , 78., , (d), , 7, , (d) 1.02  10 7 N / C downwards, , 77., , 26.2 N / C, , 1, q, ., 4[RPET,  0 d1997], , (c), , Four charges are placed on corners of a square as shown in figure, having side of 5 cm . If Q is one microcoulomb, then electric field, intensity at centre will be, , 76., , (a) Zero, , A charged water drop whose radius is 0.1 m is in equilibrium in, an electric field. If charge on it is equal to charge of an electron,, then intensity of electric field will be (g  10 ms 1 ), (a), , Electrostatics, 1, (b), 4  0, , me, m, , (b), , 2m e, m, , (d), , me, 2m , , A proton is accelerated through 50,000 V. Its energy will increase by, (a) 5000 eV, , (b) 8  10 15 J, , (c) 5000 J, , (d) 50,000 J, , When a proton is accelerated through 1V, then its kinetic energy will, be, [CBSE PMT 1999], (a) 1840 eV, , (b) 13.6 eV, , (c) 1 eV, , (d) 0.54 eV, , An electron enters between two horizontal plates separated by 2mm, and having a potential difference of 1000V. The force on electron is, (a), , 8  10 12 N, , (b) 8  10 14 N, , (c), , 8  10 9 N, , (d) 8  10 14 N, , If a charged spherical conductor of radius 10 cm has potential V, , Two metal spheres of radii R1 and R 2 are charged to the same, potential. The ratio of charges on the spheres is, , at a point distant 5 cm from its centre, then the potential at a, , [KCET 1999], , point distant 15 cm from the centre will be, [SCRA 1998; JIPMER 2001, 02], 1, 2, V, V, (a), (b), 3, 3, 3, V, (c), (d) 3 V, 2, Two unlike charges of magnitude q are separated by a distance, , 2d . The potential at a point midway between them is, , (a), (c), 89., , R1 : R 2, R12 : R 22, , (b), , R1 : R 2, , (d), , R13: R 23, , Electric charges of 10 C,  5 C,  3 C, , and 8 C are, , placed at the corners of a square of side 2 m. the potential at the, centre of the square is, [JIPMER 1999], [KCET (Engg./Med.) 1999], (a) 1.8 V, , (b) 1.8  10 6 V, , In O.P public school campus near Andhra Bank Old mangal bazar Sahjanwa Gorakhpur, Contact-9936998882,9453081912

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12 Electrostatics, (c), 90., , 1.8  10 5 V, , (d) 1.8  10 4 V, , What is the magnitude of a point charge which produces an electric, field of 2 N/coulomb at a distance of 60 cm, ( 1 / 4 0  9  10 9 N  m 2 / C 2 ), , 91., , 97., , [MP PET 2000; RPET 2001], , (a), , 8  10 11 C, , (b), , 2  10 12 C, , (c), , 3  10 11 C, , (d), , 6  10 10 C, , (b) 2, , (c) 3, , (d) 4, , displacement of a charge Q in the electric, E  e 1ˆi  e 2 ˆj  e 3 kˆ is rˆ  aˆi  bˆj . The work done is, , The, , field, , [EAMCET (Engg.) 2000], , The electric field due to a charge at a distance of 3 m from it is 500, N/coulomb., The, magnitude, of, the, charge, is, ,  1, N m ,  9  10 9, , , 4, , coulomb2 , 0, , , (a) 1, , (a), , Q(ae1  be 2 ), , (b) Q (ae1 )2  (be 2 )2, , (c), , Q(e 1  e 2 ) a 2  b 2, , (d) Q( e 12  e 22 ) (a  b), , 2, , 92., , [MP PMT 2000], , (a) 2.5 micro-coulomb, , (b) 2.0 micro-coulomb, , (c) 1.0 micro-coulomb, , (d) 0.5 micro-coulomb, , Two charges of 4 C each are placed at the corners A and B of an, equilateral triangle of side length 0.2 m in air. The electric potential, , 98., , 99., ,  1, N -m ,  9  10 9, at C is , , 4, , C 2 , 0, , 2, , The potential at a point, due to a positive charge of 100 C at a, distance of 9m, is, [KCET (Med.) 2000], (a), , 10 4 V, , (b) 10 5 V, , (c), , 10 6 V, , (d) 10 7 V, , There is a solid sphere of radius ‘R’ having uniformly distributed, charge. What is the relation between electric field ‘E’ (inside the, sphere) and radius of sphere ‘R’ is, [Pb. PMT 2000], , [EAMCET (Med.) 2000], , 93., , 94., , (a), , 9  10 4 V, , (b) 18  10 4 V, , (c), , 36  10 4 V, , (d), , 36  10 4 V, , Electric field strength due to a point charge of 5 C at a distance, of 80 cm from the charge is, [CBSE PMT 2000], (a), , 8  10 4 N/C, , (b) 7  10 4 N/C, , (c), , 5  10 N/C, , 4  10 N/C, , 4, , (d), , 100., , (c), 95., , (b), (d), , , V  0 and E  0, , V  0 and E  0, , Two positive point charges of 12 C and 8 C are 10cm apart., The work done in bringing them 4 cm closer is, [AMU 2000], , 96., , (c), , E, , (a) 5.8 J, , (b) 5.8 eV, , (c) 13 J, , (d) 13 eV, , 101., , 102., , E  R2, , Two charges 5 C and 10 C are placed 20 cm apart. The net, electric field at the mid-Point between the two charges is, (a), , 4.5  10 6 N/C directed towards 5 C, , (b), , 4.5  10 6 N/C directed towards 10 C, , (c), , 13.5  10 6 N/C directed towards 5 C, , Which of the following is deflected by electric field, (a) X-rays, , (b)  -rays, , (c) Neutrons, , (d)  -particles, , As shown in the figure, charges q and q are placed at the, vertices B and C of an isosceles triangle. The potential at the, vertex A is, [MP PET 2000], , 1, 2q, ., 2, 4 0, a  b2, (b) Zero, 1, q, (c), ., 2, 4 0, a  b2, , 2, , (d), M, , (d), , (a), , 3, , 1, , E  R 1, , [CPMT 2000], , Three identical point charges, as shown are placed at the vertices of, an isosceles right angled triangle. Which of the numbered vectors, coincides in direction with the electric field at the mid-point M of, the hypotenuse, [AMU 2000], , 4, , , R3, , (b), , (d) 13.5  10 6 N/C directed towards 10 C, , [AMU 2000], , V  0 and E  0, , V  0 and E  0, , E  R 2, , 4, , Ten electrons are equally spaced and fixed around a circle of radius, R. Relative to V = 0 at infinity, the electrostatic potential V and the, electric field E at the centre C are, , (a), , (a), , 103., , 1, 4 0, , ., , (q), , A, , a, b, B, +q, , b, –q, , C, , a2  b 2, , Consider the points lying on a straight line joining two fixed, opposite charges. Between the charges there is, [Roorkee 2000], , In O.P public school campus near Andhra Bank Old mangal bazar Sahjanwa Gorakhpur, Contact-9936998882,9453081912

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RADIATION INSTITUTE, for JEE (Main & Adv.)/NEET, FOUNDATION, PRE-FOUNDATION with Board,, Electrostatics, (a), (b), (c), (d), 104., , No point where electric field is zero, Only one point where electric field is zero, No point where potential is zero, Only one point where potential is zero, , 109., , 5, , A charged particle of mass 5  10 kg is held stationary in space, by placing it in an electric field of strength 10 7 NC 1 directed, vertically downwards. The charge on the particle is, [EAMCET 2000], , 105., , (a), ,  20  10 5 C, , (b), ,  5  10 5 C, , (c), , 5  10 5 C, , (d), , 20  10 5 C, , (a), , 107., , An electron is moving towards x-axis. An electric field is along ydirection then path of electron is [RPET 2000], (a) Circular, , (b) Elliptical, , (c) Parabola, , (d) None of these, , An electron enters in an electric field with its velocity in the, direction of the electric lines of force. Then, [MP PMT 2000], , (c) The velocity of the electron will decrease, (d) The velocity of the electron will increase, 111., , Q, , An electron of mass m and charge e is accelerated from rest, through a potential difference V in vacuum. The final speed of the, electron will be, [MP PMT 2000; AMU (Engg.) 2000], , 2 q, 2 2, , (c), , 2q, , (d), , q, , (a), +q, , +q, , Two electric charges 12 C and 6 C are placed 20 cm apart in, air. There will be a point P on the line joining these charges and, outside the region between them, at which the electric potential is, zero. The distance of P from 6 C charge is, (a) 0.10 m, (b) 0.15 m, (c) 0.20 m, (d) 0.25 m, In the given figure distance of the point from A where the electric, field is zero is, [RPMT 2000], , 112., , 2eV / m, , q, , q, , q, , (d), , 2eV / m, , (b) 4V, , (c) 8V, 113., , (d) 16V, , The dimension of (1/2)  0 E 2 ( 0 : permittivity of free space; E :, electric field) is, , 20 C, , q, , eV / m, , [Pb. PMT 2000], [EAMCET, (a) 2V2000], , 80 cm, , (a) 20 cm, (b) 10 cm, (c) 33 cm, (d) None of these, Figures below show regular hexagons, with charges at the vertices., In which of the following cases the electric field at the centre is not, zero, [AMU 2000], , (b), , The radius of a soap bubble whose potential is 16V is doubled. The, new potential of the bubble will be, , B, , 10 C, , q, , V e /m, , (c), , a, , A, , 108., , (d) 4, , (b) The path of the electron will be a parabola, , 1 2, , (b), , 106., , (b) 2, , (c) 3, , (a) The path of the electron will be a circle, , Three charges Q,  q and q are placed at the vertices of a rightangled isosceles triangle as shown. The net electrostatic energy of, the configuration is zero if Q is equal to, [IIT-JEE (Screening) 2000], , q, , 110., , (a) 1, , 13, , 114., , [IIT-JEE (Screening) 2000; KCET 2000], , 1, , (a), , MLT, , (c), , ML1 T 2, , (b), , ML2 T 2, , (d), , ML2 T 1, , In the rectangle, shown below, the two corners have charges, q1  5 C and q 2  2.0 C . The work done in moving a, charge, , 3.0 C, , 1 / 4 0  10, , 10, , from, 2, , B, , to, , N -m /C ), A, 5 cm, , q, B, , q, , q, , q, (1), , 2q, , 2q, , 2q, , q, , q, , –q, , 15 cm, , (2), , q, , 115., , q, , 2q, , (take, , [AMU 2001], , q1, , –q, , q, , is, , A, , 2, , (a) 2.8 J, , (b) 3.5 J, , (c) 4.5 J, , (d) 5.5 J, , q2, , A cube of a metal is given a positive charge Q. For the above system,, which of the following statements is true, [MP PET 2001], , 2q, , 2q, (3), , 2q, , q, , (a) Electric potential at the surface of the cube is zero, , (4), , In O.P public school campus near Andhra Bank Old mangal bazar Sahjanwa Gorakhpur, Contact-9936998882,9453081912

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14 Electrostatics, (b) Electric potential within the cube is zero, , a2, b2, (d), (c) Electric field is normal to the surface of the cube, b2, a2, 122. Potential at a point x-distance from the centre inside the conducting, (d) Electric field varies within the cube, sphere of radius R and charged with charge Q is, If q is the charge per unit area on the surface of a conductor, then, [MP PMT 2001], the electric field intensity at a point on the surface is [MP PET 2001; UPSEAT 2001], Q, Q, (a), (b), R, x,  q , (a)   normal to surface, Q, (c), (d) xQ,  0 , x2,  q , 123. Electric field intensity at a point in between two parallel sheets with,  normal to surface, (b) , , like charges of same surface charge densities ( ) is, 2, ,  0, (c), , 116., , (c), ,  q, , ,  0, ,  q, (d) ,  2 0, 117., , [MP PMT 2001], , ,  tangential to surface, , , , A hollow conducting sphere of radius R has a charge (Q) on its, surface. What is the electric potential within the sphere at a distance, R, r, from its centre, [MP PMT 2001;, 3, , 124., , UPSEAT 2001; MP PET 2001, 02; Orissa JEE 2005], , (c), 118., , 1, 4 0, , (b), , Q, R, , 119., , 4 0, , Q, r, , 1, , Q, , 125., , (c), , 1, , 4 0 r 2, , 126., , (b) 60 V, (d) 40 V, , 4 0, , Qq, l, , 1, Qql, 4 0, , (d), , (b), , 1, , 0, , In an hydrogen atom, the electron revolves around the nucleus in an, orbit of radius 0.53  10 10 m . Then the electrical potential, produced by the nucleus at the position of the electron is, (a) – 13.6 V, , (b) – 27.2 V, , (c) 27.2 V, , (d) 13.6 V, , Consider two point charges of equal magnitude and opposite sign, separated by a certain distance. The neutral point due to them, Does not exist, Will be in mid way between them, Lies on the perpendicular bisector of the line joining the two, Will be closer to the negative charge, , Two small spherical balls each carrying a charge Q  10 C (10, micro-coulomb) are suspended by two insulating threads of equal, lengths 1m each, from a point fixed in the ceiling. It is found that in, , 60o, , (b) 1.8 N, , 4 0 l 2, , (c) 0.18 N, (d) None of the above, , (d) Zero, , q, q, (d),  V, mV, m , Two spheres A and B of radius ‘a’ and ‘b’ respectively are at same, electric potential. The ratio of the surface charge densities of A and, B is, [MP PMT 2001], a, b, (a), (b), b, a, , 2, , (a) 18 N, , Qq, , A particle of mass ‘m’ and charge ‘q’ is accelerated through a, potential difference of V volt, its energy will be, [MP PET 2001], (a) qV, (b) mqV, , , 0, , equilibrium threads are separated by an angle 60 o between them,, as shown in the figure. What is the tension in the threads (Given:, 1,  9  10 9 Nm / C 2 ), [MP PET 2001; Pb PET 2003], (4 0 ), , 127., , (c), 121., , (c) Zero, , (a), (b), (c), (d), , A charge (q) and another charge (Q) are kept at two points A, and B respectively. Keeping the charge (Q) fixed at B, the charge, (q) at A is moved to another point C such that ABC forms an, equilateral triangle of side l. The net work done in moving the, charge (q) is, [MP PET 2001], (a), , 120., , (d), , 1, , A spherical conductor of radius 2m is charged to a potential of 120, V. It is now placed inside another hollow spherical conductor of, radius 6m. Calculate the potential to which the bigger sphere would, be raised, [KCET 2001], (a) 20 V, (c) 80 V, , (b), , (a), , ,  tangential to surface, , , , (a) Zero, , , 2 0, , 128., , Q, , Q, , A ball of mass 1 g and charge 10 8 C moves from a point A., where potential is 600 volt to the point B where potential is zero., Velocity of the ball at the point B is 20 cm/s. The velocity of the ball, at the point A will be, [KCET 2001], (a) 22.8 cm/s, , (b) 228 cm/s, , (c) 16.8 m/s, , (d) 168 m/s, , The acceleration of an electron in an electric field of magnitude 50, , V/cm, if e/m value of the electron is 1.76  1011 C/kg, is, (a), , 8.8  1014 m/sec, , 2, , (b) 6.2  1013 m/sec, , 2, , In O.P public school campus near Andhra Bank Old mangal bazar Sahjanwa Gorakhpur, Contact-9936998882,9453081912

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RADIATION INSTITUTE, for JEE (Main & Adv.)/NEET, FOUNDATION, PRE-FOUNDATION with Board,, Electrostatics, (c), 129., , 5.4  1012 m/sec, , (d) Zero, , 2, , Three charges Q, (q) and (q) are placed at the vertices of an, equilateral triangle of side l as shown in the figure. If the net, electrostatic energy of the system is zero, then Q is equal to, (a), ,  q,  ,  2, , (c), , (c) 0.1 V/m downward, , l, , +q, , A positively charged particle moving along x-axis with a certain, velocity enters a uniform electric field directed along positive y-axis., Its, [AMU (Engg.) 2001], , 138., , (b) Horizontal velocity changes but vertical velocity remains, constant, (d) Neither vertical nor horizontal velocity changes, Electric potential at any point is V  5 x  3 y  15 z , then the, magnitude of the electric field is [MP PET 2002], (a), , 3 2, , (b), , (c), , 5 2, , (d) 7, , 139., , 4 2, , The work done in bringing a 20 coulomb charge from point A to, point B for distance 0.2m is 2J. The potential difference between the, two points will be (in volt), , 140., , [RPET 1999; MP PMT 2002; AIEEE 2002], , 134., , 135., , (a) 0.2, , (b) 8, , (c) 0.1, , (d) 0.4, , (a), , 5  10 4 C, , (b) 5  10 10 C, , (c), ,  18  10 6 C, , (d), , Two point charges 9 e and e are at 16 cm away from each, other. Where should another charge q be placed between them so, that the system remains in equilibrium, (a) 24 cm from 9 e, , (b) 12 cm from 9 e, , (c) 24 cm from e, , (d) 12 cm from e, , If 3 charges are placed at the vertices of equilateral triangle of, charge ‘q’ each. What is the net potential energy, if the side of, equilateral  is l cm, [AIEEE 2002], (a), , q2, 4 0 l, , (b), , 2q 2, 4 0 l, , (c), , 3q 2, 4 0 l, , (d), , 4q2, 4 0 l, , 1, , 1, , (b) Point beyond 10 metres, , (c) Interior point, , (d) Outer point, , 141., , (b) 0.65 m, (d) 0.350 m, , If identical charges (q) are placed at each corner of a cube of side, , b, then electric potential energy of charge (q) which is placed at, , If 4  10 eV energy is required to move a charge of 0.25, coulomb between two points. Then what will be the potential, difference between them, [MHCET 2002], , centre of the cube will be, , (a) 178 V, , (b) 256 V, , (a), , (b), , (c) 356 V, , (d) None of these, , 8 2q 2, 4 0 b, , (c), ,  4 2q 2,  0 b, , (d), , [CBSE PMT 2002], , Kinetic energy of an electron accelerated in a potential difference of, 100 V is, [AFMC 1999; MP PMT 2002], 1.6  10 17 J, , (b) 1.6  10 21 J, , (c), , 1.6  10 29 J, , (d) 1.6  10 34 J, , 1, , [Kerala PET 2002], , 20, , (a), , 1, , The distance between charges 5  10 11 C and  2.7  10 11 C is, 0.2 m. The distance at which a third charge should be placed in, order that it will not experience any force along the line joining the, two charges is, , A hollow sphere of charge does not produce an electric field at any[MNR 1985; RPET 2001; DPMT 2002;, (a) 0.44 m, Kerala PMT 2004; Pb PET 2004; Orissa PMT 2004], (c) 0.556 m, (a) Point beyond 2 metres, ,  5  10 9 C, , [MP PET 2002], , (c) Both vertical and horizontal velocities change, , 133., , A charged particle of mass 0.003 gm is held stationary in space by, placing it in a downward direction of electric field of, , [Orissa JEE 2002], l, , +q, , (a) Vertical velocity changes but horizontal velocity remains, constant, , 132., , (d) 0.1 V/m upward, , 6  10 4 N / C . Then the magnitude of the charge is, , (q), , (d) Zero, , 131., , [MP PET 2002], , [MP PET 2001] (b) 10 V/m downward, (a) 10 V/m upward, , 137., l, , 15, , A drop of 10 6 kg water carries 10 6 C charge. What electric, field should be applied to balance its weight (assume, , g  10m / s 2 ), , Q, , (b) (q), , 130., , 136., , 142., ,  8 2q 2,  0 b,  4q2, 3 0 b, , An electron having charge ‘e’ and mass ‘m’ is moving in a uniform, electric field E. Its acceleration will be [AIIMS 2002], (a), , e2, m, , (b), , E 2e, m, , In O.P public school campus near Andhra Bank Old mangal bazar Sahjanwa Gorakhpur, Contact-9936998882,9453081912

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16 Electrostatics, (c), 143., , eE, m, , (d), , mE, e, A, , Cathode rays travelling from east to west enter into region of, electric field directed towards north to south in the plane of paper., The deflection of cathode rays is towards, , C, , [CPMT 2002], , 144., , (a) East, , (b) South, , (c) West, , (d) North, , An  -particle is accelerated through a potential difference of 200V., The increase in its kinetic energy is, , B, , 151., , [UPSEAT 2002], , 145., , 148., , VB  VC, , (c), , V A  VB, , (d), , V A  VC, , A point charge is kept at the centre of a metallic insulated spherical, shell. Then, [Orissa JEE 2003], , (c) 400 eV, , (d) 800 eV, , (b) Electric field inside the sphere is zero, (c) Net induced charge on the sphere is zero, , A simple pendulum of period T has a metal bob which is, negatively charged. If it is allowed to oscillate above a positively, charged metal plate, its period will, , (d) Electric potential inside the sphere is zero, 152., , An electron moving with the speed 5  10 6 per sec is shooted, , (a) Remains equal to T, , (b) Less than T, , parallel to the electric field of intensity 1  10 3 N/C . Field is, , (c) Greater than T, , (d) Infinite, , responsible for the retardation of motion of electron. Now evaluate, the distance travelled by the electron before coming to rest for an, , A charged particle of mass m and charge q is released from rest, , (a), , Eq 2m, 2t 2, , (b), , 2E 2 t 2, mq, , (c), , E 2q 2t 2, 2m, , (d), , Eqm, t, , instant (mass of e  9  10 31 Kg. charge  1.6  10 19 C), , 153., , (b) 1/1840 keV, , (c) 1 keV, , (d) 920 keV, , (c) Zero, , (c), , (q  Q) 2, 4 0 R, , 154., , 2Q, 4 0 R, , , , 2q, 4 0 R, , (d), , The electric potential at the surface of an atomic nucleus ( Z =, [CPMT 1990; Pb. PMT 2002; BVP 2003; MP PET 2004], , [BHU 2003], , 0.9  10 6 N / C, , 155., , 156., , 2Q, 4 0 R, 2Q, 4 0 R, , [MP PMT 2003], , 50) of radius 9.0× 10 13 cm is, , (b) 1.8  10 N / C, , (b), , An electron enters in high potential region V 2 from lower potential, , (d) No change in direction perpendicular to field, , A thin spherical conducting shell of radius R has a charge q., Another charge Q is placed at the centre of the shell. The, R, electrostatic potential at a point p a distance, from the centre of, 2, the shell is, [AIEEE 2003], (a), , (d) 0.7 cm, , (c) No change in direction of field, , 6, , (d), , (c) 7 cm, , (b) Will change in direction but not in magnitude, , A conducting sphere of radius R  20 cm is given a charge, , 3.6  10 N / C, , (b) 0.7 mm, , (a) Will increase, , (a) 1840 keV, , 6, , [KCET 2003], (a) 7 m, , region V1 then its velocity, , A proton is about 1840 times heavier than an electron. When it is, accelerated by a potential difference of 1 kV, its kinetic energy will, be [AIIMS 2003; DCE 2001], , (a), , 150., , (b), , (a) Electric field out side the sphere is zero, , Q  16 C . What is E at centre, , 149., , VC  VB, , (b) 200 eV, , in a uniform electric field E. Neglecting the effect of gravity, the, kinetic energy of the charged particle after ‘t’ second is, , 147., , (a), , (a) 100 eV, , [AIEEE 2002; CBSE PMT 2001], , 146., , P, , , , (a) 80 volts, , (b) 8 × 10 6 volts, , (c) 9 volts, , (d) 9 × 10 5 volts, , A pellet carrying charge of 0.5 coulombs is accelerated through a, potential of 2,000 volts. It attains a kinetic energy equal to [NCERT 1973; CPM, (a) 1000 ergs, , (b) 1000 joules, , (c) 1000 kWh, , (d) 500 ergs, , A particle has a mass 400 times than that of the electron and charge, is double than that of a electron. It is accelerated by 5 V of potential, difference. Initially the particle was at rest, then its final kinetic, energy will be, [MP PMT 1990; DPMT 1999], , q, 4 0 R, , A hollow conducting sphere is placed in an electric field produced, by a point charge placed at P as shown in figure. Let VA , VB , VC be, the potentials at points A, B and C respectively. Then [Orissa JEE 2003], , 157., , (a) 5 eV, , (b) 10 eV, , (c) 100 eV, , (d) 2000 eV, , An electron (charge = 1.6  10 19 coulomb) is accelerated through, a potential of 1,00,000 volts. The energy required by the electron is, , In O.P public school campus near Andhra Bank Old mangal bazar Sahjanwa Gorakhpur, Contact-9936998882,9453081912

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RADIATION INSTITUTE, for JEE (Main & Adv.)/NEET, FOUNDATION, PRE-FOUNDATION with Board,, , 158., , (a), , 1.6  10 24 joule, , (b) 1.6  10 14 erg, , (c), , 0.53  10 14 joule, , (d) 1.6  10 14 joule, , The charge given to a hollow sphere of radius 10 cm is 3.2×10, coulomb. At a distance of 4 cm from its centre, the electric potential, will be, [MP PMT 1990], , –19, , (a), , 9, , 28.8  10 volts, , (c) 2.88 volts, 159., , 166., , (b), , 167., , 288 volts, , Electrostatics 17, When a charge of 3 coulombs is placed in a uniform electric field, it, experiences a force of 3000 Newton. Within this field, potential, difference between two points separated by a distance of 1 cm is[MP PMT 1986, (a) 10 volts, , (b) 90 volts, , (c) 1000 volts, , (d) 3000 volts, , There are two equipotential surface as shown in figure. The distance, between them is r. The charge of –q coulomb is taken from the, surface A to B, the resultant work done will be, , (d) Zero, (a), , Work done in moving a positive charge on an equipotential surface, is, [BCECE 2004], , W, , (b) W , , (a) Finite, positive but not zero, (b) Finite, negative but not zero, (c) Zero, , (c), , 1 q, 4 o r, 1 q, 4 0 r 2, , W , , (d) Infinite, 160., , A charge of 10 e.s.u. is placed at a distance of 2 cm from a charge of, 40 e.s.u. and 4 cm from another charge of 20 e.s.u. The potential, energy of the charge 10 e.s.u. is (in ergs), , 161., , (b) 112.5, , (c) 150, , (d) 250, , A table tennis ball which has been covered with conducting paint is, suspended by a silk thread so that it hang between two plates, out, of which one is earthed and other is connected to a high voltage, generator. This ball, , 168., , CBSE PMT 1993, 99; Pb. PMT 1999; BHU 2000, 02], , 169., , (a) Decreases, , (b) Increases, , (c) Remains unchanged, , (d) Becomes zero, , A hollow metal sphere of radius 5cm is charged such that the, potential on its surface is 10V. The potential at a distance of 2cm, from the centre of the sphere, [MP PET 1992; MP PMT 1996], (a) Zero, , (b) 10 V, , (c) Swing backward and forward hitting each plate in turn, , (c) 4 V, , (d) 10/3 V, , 163., , 164., , 165., , 170., , 1, e.s.u., 4, , (b), , (c) 30 e.s.u., , (d) 36 e.s.u., , (c) + 200 V, 171., , (b) Joule = coulomb/volt, , (c) Joule = volt × ampere, , (d) Joule = volt/ampere, , (b) Increases, , (c) Remain unchanged, , (d) Become zero, , When a negative charge is taken at a height from earth's surface,, then its potential energy, [DPMT 2002], (a) Decreases, , (b) Increases, , (c) Remains unchanged, , (d) Will become infinity, , Value of potential at a point due to a point charge is, (a) Inversely proportional to square of the distance, (b) Directly proportional to square of the distance, (c) Inversely proportional to the distance, , When a positive q charge is taken from lower potential to a higher, potential point, then its potential energy will, (a) Decrease, , (d) – 200 V, [MP PET 1996], , State which of the following is correct [CPMT 1974, 80], (a) Joule = coulomb × volt, , The work done in carrying a charge of 5 C from a point A to a, point B in an electric field is 10mJ. The potential difference, [Haryana CEE 1996], (VB  VA ) is then, [MP PMT 1991], (a) + 2kV, (b) – 2 kV, , A sphere of 4 cm radius is suspended within a hollow sphere of 6, cm radius. The inner sphere is charged to potential 3 e.s.u. and the, outer sphere is earthed. The charge on the inner sphere is, (a) 54 e.s.u., , B, , When one electron is taken towards the other electron, then the, electric potential energy of the system, [RPET 1999;, , (b) Hangs without moving, (d) Is attracted to earthed plate and stays there, , r, , (d) W = zero, , (a) Is attracted towards high voltage plate and stays there, , 162., , A, , 1 q, 4 0 r 2, , [CPMT 1976; MP PET 1989], (a) 87.5, , [, , (d) Directly proportional to the distance, 172., , 173., , Electric potential of earth is taken to be zero because earth is a good, (a) Insulator, , (b) Conductor, , (c) Semiconductor, , (d) Dielectric, , There is 10 units of charge at the centre of a circle of radius 10m., The work done in moving 1 unit of charge around the circle once is, [EAMCET (Med.) 1995; AIIMS 2000; Pb. PMT 2000], (a) Zero, , (b) 10 units, , In O.P public school campus near Andhra Bank Old mangal bazar Sahjanwa Gorakhpur, Contact-9936998882,9453081912, , [

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18 Electrostatics, (c) 100 units, 174., , (d) 1 unit, , (c), , Two parallel plates separated by a distance of 5mm are kept at a, potential difference of 50 V . A particle of mass 10 15 kg and, , 181., , 7.11  10 6 C, , (d) None of these, , A charged particle is suspended in equilibrium in a uniform vertical, electric field of intensity 20000 V/m. If mass of the particle is, 9.6  10 16 kg , the charge on it and excess number of electrons on, , charge 10 11 C enters in it with a velocity 10 7 m / s. The, acceleration of the particle will be, , the particle are respectively (g  10 m / s 2 ), , [MP PMT 1997], , 175., , 8, , (a), , 10 m / s, , 2, , (c), , 10 5 m / s 2, , [Pb. PMT 2003], , (b), , 5  10 m / s, , (a), , 4.8  10, , (d), , 2  10 3 m / s 2, , (c), , 3.8  10 19 C, 2, , Three point charges are placed at the corners of an equilateral, triangle. Assuming only electrostatic forces are acting, , 182., , (a) The system can never be in equilibrium, , (c), 183., , (d) The system will be in equilibrium if the charges have the same, magnitudes but different signs, If an insulated non-conducting sphere of radius R has charge density,  . The electric field at a distance r from the centre of sphere, , 177., , 178., , (a), , R, 3 0, , (c), , r, 3 0, , [BHU 2003], (b), , (d), , 184., , r, 0, , (d) 3000 V/m, , (b), , Q, 4  0 R, , (d), , Q, 8 0 R, Q, 2 0 R, , Four charges Q,  Q,  Q,  Q are placed at the corners of a, square taken in order. At the centre of the square, [RPMT 2003], (a), , E  0, V  0, , (b), , E  0, V  0, , (c), , E  0, V  0, , (d), , E  0, V  0, , The radius of nucleus of silver (atomic number = 47) is, , (a), , Two plates are at potentials –10 V and +30 V. If the separation, between the plates be 2 cm. The electric field between them is, (c) 500 V/m, , 2.8  10 19 C, 1, , (e  1.6  10 19 C), , 0, , (b) 1000 V/m, , C, 4, , 3.4  10 14 m . The electric potential on the surface of nucleus is, , 3 R, , (a) 2000 V/m, , (d), , (a) 0, , (c) The system will be in equilibrium if the charges have different, magnitudes and different signs, , (r  R) will be, , (b) 5.8  10, , C, 3, , 19, , The potential at a distance R/2 from the centre of a conducting, sphere of, radius, R will be, [RPMT 2003], [KCET, 2002], , (b) The system will be in equilibrium if the charges rotate about, the centre of the triangle, , 176., , 19, , 2, , 5, , [Pb. PET 2003], , 1.99  10 6 volt, , (b), , 2.9  10 6 volt, , (d) 0.99  10 6 volt, 4.99  10 6 volt, Charges[Pb., q, 2PET, q, 3q2000], and 4q are placed at the corners A, B, C and D of, a square as shown in the following figure. The direction of electric, field at the centre of the square is along, D, C, [MP PMT 2004], (c), , 185., , 4q, , The electric potential inside a conducting sphere, , 3q, , [RPMT 2002], O, , (a) Increases from centre to surface, (b) Decreases from centre to surface, (c) Remains constant from centre to surface, , (a) AB, (c) BD, , (d) Is zero at every point inside, 179., , 186., , The wrong statement about electric lines of force is, (a) These originate from positive charge and end on negative, charge, (b) They do not intersect each other at a point, , 187., , (a), , x  2 and x  9, , (b), , x  1 and x  5, , (c), , x  4 and x  12, , (d), , x  2 and x  2, , Equipotential surfaces associated with an electric field which is, increasing in magnitude along the x-direction are, [AIIMS 2004], , A charge produces an electric field of 1 N/C at a point distant 0.1 m, from it. The magnitude of charge is, , (a) Planes parallel to yz-plane, , [RPET 2002], , (b) Planes parallel to xy-plane, , (a), , 1.11  10 12 C, , (b), , 9.11  10 12 C, , (b) CB, (d) AC, , Point charge q1  2 C and q 2  1 C are kept at points, , (d) They have physical existence, 180., , 2q, , B, , x  0 and x  6 respectively. Electrical potential will be zero at, points, [MP PMT 2004], , [RPMT 2002], , (c) They have the same form for a point charge and a sphere, , q, A, , (c) Planes parallel to xz-plane, (d) Coaxial cylinders of increasing radii around the x-axis, , In O.P public school campus near Andhra Bank Old mangal bazar Sahjanwa Gorakhpur, Contact-9936998882,9453081912

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RADIATION INSTITUTE, for JEE (Main & Adv.)/NEET, FOUNDATION, PRE-FOUNDATION with Board,, 188., , 189., , A bullet of mass 2 gm is having a charge of 2 C . Through what, , V/m. The, , potential difference must it be accelerated, starting from rest, to, acquire a speed of 10 m / s, [CBSE PMT 2004], , (g  9.8 m / s ), , (a) 5 kV, , (b) 50 kV, , (c) 5 V, , (d) 50 V, [Orissa PMT 2004], , P, , (d) P and R, , Q, , 196., , R, , Figure shows three points A, B and C in a region of uniform electric, field E . The line AB is perpendicular and BC is parallel to the field, lines. Then which of the following holds good. Where VA , VB and, VC represent the electric potential at points A, B and C respectively, , [CPMT 2004; MP PMT 2005], , 191., , (a), , VA  VB  VC, , (b), , VA  VB  VC, , (c), , VA  VB  VC, , (d), , VA  VB  VC, , 197., A, , C, , B, , In a certain charge distribution, all points having zero potential can, be joined by a circle S. Points inside S have positive potential and, points outside S have negative potential. A positive charge, which is, free to move, is placed inside S, [DPMT 2004], , 198., , [UPSEAT 2004], , (a), , 3  10 4 N, , (b), , 4  10 4 N, , (c), , 5  10 4 N, , (d) 6  10 4 N, , An infinite line charge produce a field of 7.182  10 8 N / C at a, distance of 2 cm. The linear charge density is, , (a), , 7.27  10 4 C / m, , (b) 7.98  10 4 C / m, , (c), , 7.11  10 4 C / m, , (d) 7.04  10 4 C / m, , An electron experiences a force equal to its weight when placed in, an electric field. The intensity of the field will be, [MHCET 2004], (a), , 1.7  10 11 N / C, , (b) 5.0  10 11 N / C, , (c), , 5.5  10 11 N / C, , (d) 56 N/C, , The dielectric strength of air at NTP is 3  10 6 V/ m then the, maximum charge that can be given to a spherical conductor of, radius 3 m is, [Pb. PMT 2001], (a), , 3  10 4 C, , (b), , 3  10 3 C, , (c), , 3  10 2 C, , (d), , 3  10 1 C, , As per this diagram a point charge q is placed at the origin O ., Work done in taking another point charge Q from the point A, [co-ordinates (0, a) ] to another point B [co-ordinates (a, 0)] along, the straight path AB is, , (a) It will remain in equilibrium, , [CBSE PMT 2005], , (b) It can move inside S, but it cannot cross S, , 192., , (c) It must cross S at some time, , (a) Zero, , (d) It may move, but will ultimately return to its starting point, , (b) , , (b) Zero, , (c) 6  10 q N/C, , (d) 4  10 q N/C, , (c), , Qq 2, 4 0 a, , ,  2a, , , , Y, A, ,  qQ 1  a, , , 2 ,  4 0 a  2, O, ,  qQ 1 ,  2a, 2 ,  4 0 a , , 9, , A square of side ‘a’ has charge Q at its centre and charge ‘q’ at one, of the corners. The work required to be done in moving the charge, ‘q’ from the corner to the diagonally opposite corner is, (a) Zero, , 194., , (c), , (a) 12  10 q N/C, 9, , 193., ,   qQ 1, 2,  40 a, , Infinite charges of magnitude q each are lying at x =1, 2, 4, 8... meter, on X-axis. The value of intensity of electric field at point x = 0 due to, these charges will be, [J & K CET 2004], 9, , is, , [MH CET 2004], , (c) S and R, 190., , Electrostatics 19, the thread of the pendulum, , S, , (a) P and Q, (b) S and Q, , in, , 2, , 195., , The points resembling equal potentials are, , tension, , (d) , 199., , B, , X, , [UPSEAT 2004], To charges q 1 and q 2 are placed 30 cm apart, shown in the, , (b), , Qq, 4 0 a, , figure. A third charge q 3 is moved along the arc of a circle of, , (d), , Qq, 2 0 a, , of the system is, , radius 40 cm from C to D. The change in the potential energy, , A pendulum bob of mass 30.7  10 6 kg and carrying a charge, 2  10 8 C is at rest in a horizontal uniform electric field of 20000, , q3, , 4  0, , k , where k is, q3, , [CBSE PMT 2005], , C, , (a), , 8 q2, , (b) 8 q 1, , 40 cm, , q2, q1, , D, A, , 30 cm, , B, , In O.P public school campus near Andhra Bank Old mangal bazar Sahjanwa Gorakhpur, Contact-9936998882,9453081912

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20 Electrostatics, , 200., , 201., , (c), , 6q 2, , (d), , 6q 1, , frame is perpendicular to Z axis. If a –ve point charge is placed at a, distance z away from the above frame (z<<L) then, Q, , A charged ball B hangs from a silk thread S, which makes an angle,  with a large charged conducting sheet P , as shown in the, figure. The surface charge density  of the sheet is proportional to, (a), , sin , , (b), , tan , , (c), , cos , , (d), , cot , , P, , [AIEEE 2005], , +, +, , Q, , , , +, +, , (a) – ve charge oscillates along the Z axis., (b) It moves away from the frame, , and 2q are located Bat x  0 and, x  L respectively. The location of a point on the x-axis at which, +, , (c) It moves slowly towards the frame and stays in the plane of the, frame, [AIEEE 2005], (d) It passes through the frame only once., , the net electric field due to these two point charges is zero is, (a) 8 L, (b) 4 L, , 202., , (d), , (c) QR / 4 0 d, 203., , 206., , L, 4, , Two thin wire rings each having a radius R are placed at a distance, d apart with their axes coinciding. The charges on the two rings are, q and q . The potential difference between the centres of the, two rings is, [AIEEE 2005], (a) Zero, , 2, , (b), , Q 1,  , 4 0  R, , , 1, , R 2  d 2 , , (d), , Q 1,  , 2 0  R, , , , 2, 2 , R d , , 2 ˆ, k, , (c), , 2 ˆ, k, , o, , 208., , Z = 3a, P, , 2, , Z=a, , 4 ˆ, k, , o, , 209., , (c) 120 V/m, , (d) Zero, , Charges 4Q, q and Q and placed along x-axis at positions, x  0, x  l / 2 and x  l , respectively. Find the value of q so that, force on charge Q is zero, [DPMT 2005], (a) Q, , (b) Q / 2, , (c) – Q / 2, , (d) – Q, , If an electron moves from rest from a point at which potential is 50, volt to another point at which potential is 70 volt, then its kinetic, energy in the final state will be, (a) 3.2 × 10 J, , (b) 3.2 × 10 J, , (c) 1 N, , (d) 1 dyne, , –18, , In the following diagram the work done in moving a point charge, from point P to point A, B and C is respectively as W , W and W ,, then, [J & K CET 2005], (a) W = W = W, A, C, P, (b) W = W = W = 0, (c) W > W > W, A, , x, , , , Z = a, , Two infinitely long parallel conducting plates having surface charge, densities  and  respectively, are separated by a small distance., The medium between the plates is vacuum. If  0 is the dielectric, permittivity of vacuum, then the electric field in the region between, the plates is, [AIIMS 2005], (a) 0 volts/ meter, , 205., , (b) 125 V/m, , [J & K CET 2005], , o, , (c), , (a) 150 V/m, , –10, , , , 4 ˆ, (d) , k, 204., , At a point 20 cm from the centre of a uniformly charged dielectric, sphere of radius 10 cm, the electric field is 100 V/m. The electric field, at 3 cm from the centre of the sphere will be, , Z, , o, , (b) , , 207., , 1, , Three infinitely long charge sheets are placed as shown in figure., The electric field at point P is, [IIT-JEE (Screening) 2005], (a), , Q, , S, , +, , (c) 2 L, , L, , Z-axis, , +, , Two point charges +8q, , Q, , , volts / meter, o, , (b), , (d), , , 2 o, 2, , o, , volts / meter, , volts / meter, , A, , B, , C, , A, , B, , C, , A, , B, , C, , 210., , B, , C, , B, , (d) W < W < W, A, , B, , C, , A hollow metallic sphere of radius R is given a charge Q. Then the, potential at the centre is, [Orissa JEE 2005], (a) Zero, , (c), , 1, 2Q, ., 4 0 R, , (b), , 1, Q, ., 4 0 R, , (d), , 1, Q, ., 4 0 2 R, , Electric Dipole, , Four point +ve charges of same magnitude (Q) are placed at four, corners of a rigid square frame as shown in figure. The plane of the, , In O.P public school campus near Andhra Bank Old mangal bazar Sahjanwa Gorakhpur, Contact-9936998882,9453081912

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RADIATION INSTITUTE, for JEE (Main & Adv.)/NEET, FOUNDATION, PRE-FOUNDATION with Board,, 1., , An electric dipole when placed in a uniform electric field E will, have minimum potential energy, if the positive direction of dipole, moment makes the following angle with E, [CPMT 1981; MP PMT 1987], (a), , , , (c) Zero, 2., , 3., , 4., , (c), 9., , (b)  / 2, (d), , (b) F / 2, (d) F / 8, , (a) Directly proportional to r 3, , The electric potential at a point on the axis of an electric dipole, (b) Inversely proportional to r 3, depends on the distance r of the point from the dipole as [CPMT 1982; UPSEAT 2001, (c) Directly proportional to r 2, MP PMT 1996, 2002; MP PET 2001, 05], (d) Inversely proportional to r 2, 1, 1, , , (a), (b), 11., Two charges  3.2  10 19 and  3.2  10 19 C placed at 2.4 Å, r, r2, apart form an electric dipole. It is placed in a uniform electric field, 1, of intensity 4  10 5 volt / m . The electric dipole moment is, (c)  r, (d)  3, r, (a) 15.36  10 29 coulomb  m, An electric dipole of moment p is placed in the position of stable, (b) 15.36  10 19 coulomb  m, (c), , (a), , pE cos , , (b), , pE sin, , (c), , pE(1  cos  ), , (d), ,  pE cos , , 12., , An electric dipole is kept in non-uniform electric field. It experiences, [AIIMS 2003; DCE 2001], (a) A force and a torque, , (b) A force but not a torque, , (c) A torque but not a force, , (d) Neither a force nor a torque, , An electric dipole consisting of two opposite charges of 2  10 6 C, each separated by a distance of 3 cm is placed in an electric field of, , (a), , 12  10 1 N m, , (b) 12  10 3 N m, , (c), , 24  10 1 N m, , (d), , 13., , 24  10 3 N m, , An electric dipole of moment p is placed normal to the lines of, , pE, , (b), , (c), , 2 pE, , (d) Zero, , The distance between the two charges q and q of a dipole is, r . On the axial line at a distance d from the centre of dipole, the, intensity is proportional to, [CPMT 1977], (a), , q, d2, , (b), , An electric dipole of moment p is placed at the origin along the x axis. The electric field at a point P , whose position vector makes an, angle  with the x -axis, will make an angle ..... with the x -axis,, 1, where tan   tan , [MP PMT 1994], 2, (a) , , (b) , , (c)   , , (d)   2, , An electric dipole is placed along the x  axis at the origin O . A, point P is at a distance of 20 cm from this origin such that OP, [MP PMT1987], makes an angle, with the x-axis. If the electric field at P makes, 3, an angle  with the x-axis, the value of  would be, (a), , , 3, , (b), , (c), , 2, 3, , (d), ,  2 pE, , (a), , qr, d2, , 7.68  10 29 coulomb  m, , (d) 7.68  10 19 coulomb  m, , force of electric intensity E , then the work done in deflecting it, through an angle of 180 is, [BVP 2003], , 8., , (b) 1.6  10 29, , (c) F / 4, , 2  10 5 N/C. The maximum torque on the dipole will be, , 7., , 1.6  10 19, , (a) 2F, , 10., , [MP PET 1993], , 6., , 21, , (c) 3.2  10 19, (d) 3.2  10 29, The electric field due to a dipole at a distance r on its axis is, [MP PMT 1993; RPET 2001;, [MNR 1986], MP PET/PMT 2002; BCECE 2003], , A given charge is situated at a certain distance from an electric, dipole in the end-on position experiences a force F. If the distance of, the charge is doubled, the force acting on the charge will be, , equilibrium in uniform electric field of intensity E . It is rotated, through an angle  from the initial position. The potential energy, of electric dipole in the final position is, , 5., , d3, , Electrostatics, qr, (d), d3, , An electron and a proton are at a distance of 1 Å . The moment of, this dipole will be (C  m), [CPMT 1984], (a), , 3 / 2, , q, , 14., ,  3, ,  tan 1 ,  2 , 3, , , , , ,  3, , tan 1 ,  2 , , , , Electric charges q, q,  2q are placed at the corners of an, equilateral triangle ABC of side l . The magnitude of electric, dipole moment of the system is [MP PMT 1994], (a), (c), , ql, , 3 ql, , (b), , 2ql, , (d), , 4 ql, , In O.P public school campus near Andhra Bank Old mangal bazar Sahjanwa Gorakhpur, Contact-9936998882,9453081912

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22 Electrostatics, 15., , The torque acting on a dipole of moment P in an electric field E, is [MP PMT 1994; CPMT 2001], (a), , PE, , (c) Zero, 16., , (b), , PE, , (d), , EP, , 22., , 23., , The electric field at a point on equatorial line of a dipole and, direction of the dipole moment, [MP PET 1995], , (a) Force and torque both, (b), (c) Torque but no force, (d), The electric intensity due to a dipole, charge of 500 C , at a point on the, one of the charges in air, is, , [CBSE PMT 2001], (a), , (b) Will be in opposite direction, , (c) 13.1  1111 N/C, (d) 20.5  10 7 N/C, Electric potential at an equatorial point of a small dipole with dipole, moment P (r, distance from the dipole) is, , 24., , (d) Are not related, , 6.25  10 N/C, 7, , (b) 9.28  10 N/C, 7, , [MP PMT 2001], , Two opposite and equal charges 4  10 8 coulomb when placed, 2  10 2 cm away, form a dipole. If this dipole is placed in an, , (a) Zero, , external electric field 4  10 newton / coulomb , the value of, , (b), , 8, , maximum torque and the work done in rotating it through 180, will be, [MP PET 1996], (a), , 64  10 4 Nm and 64  10 4 J, , (b), , 32  10 4 Nm and 32  10 4 J, , (c), (d), 18., , 64  10, , 4, , Nm and 32  10, , 4, , (c), 25., , J, 26., , 32  10 4 Nm and 64  10 4 J, , If E a be the electric field strength of a short dipole at a point on, distance, then, , [MP PET 1999; J & K CET 2004], , (a), , Ee  2 Ea, , (b), , Ea  2 Ee, , (c), , Ea  Ee, , (d) None of the above, , 27., , (a) The net electric force on the dipole must be zero, (b) The net electric force on the dipole may be zero, , 28., , (c) The torque on the dipole due to the field must be zero, (d) The torque on the dipole due to the field may be zero, 20., , 21., , A point Q lies on the perpendicular bisector of an electrical dipole, of dipole moment p . If the distance of Q from the dipole is r, (much larger than the size of the dipole), then electric field at Q is, proportional to, [CBSE PMT 1998; JIPMER 2001, 02], (a), , p 1 and r 2, , (b), , p and r 2, , (c), , p 2 and r 3, , (d), , p and r 3, , If the magnitude of intensity of electric field at a distance x on, axial line and at a distance y on equatorial line on a given dipole, are equal, then x : y is, [EAMCET 1994], (a), , 1:1, , (b) 1 : 2, , (c), , 1:2, , (d), , 3, , 4 0 r, , 3, , 30., , 2P, 4 0 r 3, , (b) 1.3 V, , (c) 13 V, , (d) 130 V, , The potential at a point due to an electric dipole will be maximum, and minimum when the angles between the axis of the dipole and, the line joining the point to the dipole are respectively, 90 o and 180 o, , (b) 0 o and 90 o, , (c) 90 o and 0 o, (d) 0 o and 180 o, The value of electric potential at any point due to any electric dipole, is, [MP PMT 2004], , k., , p r, r2, , (b) k ., , p r, r3, , p r, p r, (d) k . 3, r2, r, An electric dipole has the magnitude of its charge as q and its dipole, moment is p. It is placed in a uniform electric field E. If its dipole, moment is along the direction of the field, the force on it and its, potential energy are respectively, [CBSE PMT 2004], (c), , k., , (a), , 2q  E and minimum, , (c) Zero and minimum, 29., , (d), , 4 0 r 2, , (a) 0.13 V, , (a), , An electric dipole is placed in an electric field generated by a point, charge, [MP PMT 1999], , P, , P, , The distance between H  and Cl  ions in HCl molecule is 1.28 Å., What will be the potential due to this dipole at a distance of 12 Å on, the axis of dipole, [MP PMT 2002], , (a), , its axial line and E e that on the equatorial line at the same, , 19., , Force but no torque, No force and no torque, of length 10 cm and having a, axis at a distance 20 cm from, , (a) Will be parallel, , (c) Will be perpendicular, , 17., , An electric dipole in a uniform electric field experiences (When it is, placed at an angle  with the field), [RPET 2000], , (b) q  E and p  E, (d) q  E and maximum, , Intensity of an electric field E due to a dipole, depends on distance r, as, [Pb. PMT 2004], (a), , E, , 1, r4, , (b), , E, , 1, r3, , (c), , E, , 1, r2, , (d), , E, , 1, r, , The ratio of electric fields on the axis and at equator of an electric, dipole will be, [RPMT 2002], (a) 1 : 1, (b) 2 : 1, (c) 4 : 1, (d) None of these, , 2 :1, , In O.P public school campus near Andhra Bank Old mangal bazar Sahjanwa Gorakhpur, Contact-9936998882,9453081912

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RADIATION INSTITUTE, for JEE (Main & Adv.)/NEET, FOUNDATION, PRE-FOUNDATION with Board,, 31., , (a) 0, , maximum torque for this dipole if E  5  10 5 N / C, , (c) 180, , (a), , 33., , 1  10 3 Nm 1, , o, , 39., , (b) 10  10 3 Nm 1, , (c) 10  10 3 Nm, (d) 1  10 2 Nm 2, A molecule with a dipole moment p is placed in an electric field of, strength E. Initially the dipole is aligned parallel to the field. If the, dipole is to be rotated to be anti-parallel to the field, the work, required to be done by an external agency is, (a) – 2pE, (b) – pE, (c) pE, (d) 2pE, An electric dipole of moment p placed in a uniform electric field, , (d) None of these, , The electric field due to an electric dipole at a distance r from its, centre in axial position is E. If the dipole is rotated through an angle, of 90° about its perpendicular axis, the electric field at the same, point will be, [J & K CET 2005], (a) E, , (b) E / 4, , (c) E / 2, [UPSEAT 2004], , (d) 2E, , Electric Flux and Gauss's Law, 1., , E has minimum potential energy when the angle between p and, , A cylinder of radius R and length L is placed in a uniform electric, field E parallel to the cylinder axis. The total flux for the surface of, the cylinder is given by, , E is, , 34., , 35., , 36., , [UPSEAT 2004], , (a) Zero, (b), 2, 3, (c) , (d), 2, A region surrounding a stationary electric dipoles has, [MP PET 1994], (a) Magnetic field only, (b) Electric field only, (c) Both electric and magnetic fields, (d) No electric and magnetic fields, Two electric dipoles of moment P and 64 P are placed in opposite, direction on a line at a distance of 25 cm. The electric field will be, zero at point between the dipoles whose distance from the dipole of, moment P is, [MP PET 2003], , [CPMT 1975; RPMT 2002; KCET 2004], , 2., , (b) R 2 / E, , (c), , (R 2  R) / E, , (d) Zero, , Electric field at a point varies as r 0 for, (b) A point charge, (c) A plane infinite sheet of charge, (d) A line charge of infinite length, , 3., , An electric charge q is placed at the centre of a cube of side  ., The electric flux on one of its faces will be, [MP PMT 1994, 95; DCE 1999, 2001; AIIMS 2001], , (b), , 25, cm, 9, , (a), , (c) 10 cm, , (d), , 4, cm, 13, , (c), , (a), , 90 o, , (b), , 0o, , (c), , 180 o, , (d), , 45 o, , 4., , 5., , Two charges  3.2  10 19 C and  3.2  10 9 C kept 2.4 Å, apart forms a dipole. If it is kept in uniform electric field of intensity, 4  10 5 volt/m, , (a), (c), , [MP PMT 2003], ,  3  10 23 J,  6  10, , 23, , J, , (b), (d), ,  2  10, , q, 4 0 a 2, , (b), , (d), , q, , 0a2, q, 0, , Total electric flux coming out of a unit positive charge put in air is, (a), , 0, , (b)  01, , (c), , (4 p 0 )1, , (d), , 4 0, , For a given surface the Gauss's law is stated as, ,  E  ds  0 . From, , [MP PMT 1995], , (a), , E is necessarily zero on the surface, , (b), , E is perpendicular to the surface at every point, , (c) The total flux through the surface is zero, ,  3  10 23 J, 23, , q, 6 0, , this we can conclude that, , then what will be its electrical energy in, , equilibrium, , 38., , 2R E, 2, , (a) An electric dipole, , then at what angle between P and E the value of torque will be, maximum, [MP PET 2002], , 37., , (a), , (a) 5 cm, , When an electric dipole P is placed in a uniform electric field E, , 23, , o, , o, , [RPMT 2003], , 32., , Electrostatics, (b) 90, , For a dipole q  2  10 6 C and d  0.01 m . Calculate the, , (d) The flux is only going out of the surface, 6., , J, , What is the angle between the electric dipole moment and the, electric field strength due to it on the equatorial line, [AFMC 2005], , A cube of side l is placed in a uniform field E , where E  Eˆi ., The net electric flux through the cube is, [Haryana CEE 1996], (a) Zero, , 2, , (b) l E, , In O.P public school campus near Andhra Bank Old mangal bazar Sahjanwa Gorakhpur, Contact-9936998882,9453081912

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24 Electrostatics, (c), 7., , 4l 2 E, , (d), , 13., , 6l 2 E, , Eight dipoles of charges of magnitude e are placed inside a cube., The total electric flux coming out of the cube will be, [MP PMT/PET 1998], (a), , (c), 8., , 8e, 0, e, , 0, , (b), , 14., , The S.I. unit of electric flux is, (a) Weber, , [KCET 2001], (b) Newton per coulomb, , (c) Volt  metre, , (d) Joule per coulomb, , q1 , q 2 , q 3 and q 4 are point charges located at points as shown in, , the figure and S is a spherical Gaussian surface of radius R. Which, of the following is true according to the Gauss’s law, , 16 e, , 0, , S, , (d) Zero, q1, , A point charge q is placed at the centre of a cube of side L . The, electric flux emerging from the cube is, , R, q4, , q2, , q3, , [CBSE PMT 1996; BCECE 2003; AIEEE 2002], (a), , (c), 9., , q, , 0, 6 qL2, , 0, , (c), 10., , 11., , (a), , , , q, , (b), ,  (E, , (d), , q, 2 0, , (b), , (d), , (b), , (c), , q, 0, 2q, , 0, 16., , (a), , (b), , (c), , (d), , Q, 0, , 17., , 0, , 4  10 3 C, , (b), ,  4  10 3 C, , (4  10 ), , through one face of cube will be, [RPET 2003; MP PET 2003; UPSEAT 2004], q, q, (a), (b), 0, 2 0, , r2, , q, q, (d), 40, 6 0, If a spherical conductor comes out from the closed surface of the, sphere then total flux emitted from the surface will be, [RPET 2003], [MP PET 2001], 1,  (the charge enclosed by surface), (a), (c), , 18., , 0, , +, +, +, , (b)  0  (charge enclosed by surface), , 1,  (charge enclosed by surface), 4 0, (d) 0, If the electric flux entering and leaving an enclosed surface, respectively is 1 and  2 the electric charge inside the surface will, be, [AIEEE 2003], (a) (1  2 ) 0, (b) ( 2  1 ) 0, (c), , 0, , 100 Q, ( 0 ), ,  (q  q  q  q ), , , 2, 3, 4,  E 2  E 3 ).dA  1, , C, (d)  4  10 3  0 C, , A charge q is placed at the centre of a cube. Then the flux passing, (c), , 100 Q, , 10 Q, ( 0 ), , 1, , 0, , 3, , 1, , 1, 1, (d), r, r3, Electric charge is uniformly distributed along a long straight wire of, radius 1mm. The charge per cm length of the wire is Q coulomb., Another cylindrical surface of radius 50 cm and length 1m, symmetrically encloses the wire as shown in the figure. The total, electric flux passing through the cylindrical surface is, , , ,  (q  q  q ), , , 2, 3,  E 2  E 3 ).d A  1, , (d) None of the above, Gauss’s law should be invalid if, [Orissa JEE 2002], (a) There were magnetic monopoles, (b) The inverse square law were not exactly true, (c) The velocity of light were not a universal constant, (d) None of these, The inward and outward electric flux for a closed surface in, [AMU, units of, N -2000], m 2 / C are respectively 8  10 3 and 4  10 3., Then the total charge inside the surface is [where  0 , permittivity constant], [KCET 2003; MP PMT 2002], (a), , (c), 12., , 1, ,  (E, s, , 15., , It is not convenient to use a spherical Gaussian surface to find the, electric field due to an electric dipole using Gauss’s theorem because, (a) Gauss’s law fails in this case, (b) This problem does not have spherical symmetry, (c) Coulomb’s law is more fundamental than Gauss’s law, (d) Spherical Gaussian surface will alter the dipole moment, According to Gauss’ Theorem, electric field of an infinitely long, straight wire is proportional to, [RPET 2000; DCE 2000], (a) r, , , , s, , 6 L2  0, , A charge q is placed at the centre of the open end of cylindrical, vessel. The flux of the electric field through the surface of the vessel, is, [MNR 1998], (a) Zero, ,  q q q, , , , 2, 3, (E1  E 2  E 3 ).d A  1, 2 0, s, , (b) Zero, , 1m, , 19., +, +, +, , 50cm, , In O.P public school campus near Andhra Bank Old mangal bazar Sahjanwa Gorakhpur, Contact-9936998882,9453081912

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RADIATION INSTITUTE, for JEE (Main & Adv.)/NEET, FOUNDATION, PRE-FOUNDATION with Board,, Electrostatics, (c), 20., , (d) (2  1 ) /  0, , q, 6(4 0 ), , 3, , [AIIMS 2003], , +q, , 3q /  0, , (b), , (c), , q /0, , (d) Zero, , 2q /  0, , q2, , +q, , (b) Only the positive charges, (c) All the charges, (d), , 25., , 26., , –2, , (b) Directly proportional to r 3, (c) Inversely proportional to r, 28., , (d) Inversely proportional to r 2, A sphere of radius R has a uniform distribution of electric charge in, its volume. At a distance x from its centre, for x  R , the electric, field is directly proportional to, [MP PMT 1994; AIIMS 1997; BCECE 2005], , –q, , q, , 1, x2, , x, , (b), , 1, x, , (d), , x2, , [IIT-JEE Screening 2004], , 2, , 1, , 1, , q1 and q1, , Gauss’s law is true only if force due to a charge varies as, [MP PMT 2004], (a), , 24., , -1, , The electric intensity due to an infinite cylinder of radius R and, having charge q per unit length at a distance r(r  R) from its axis, is [MP PMT 1993; AFMC 2000], , (c), , Consider the charge configuration and spherical Gaussian surface as, shown in the figure. When calculating the flux of the electric field, over the spherical surface the electric field will be due to, (a), , 23., , 27., , (a), , +q, , (a), , –1, , (a) Directly proportional to r 2, , S, , 22., , 3, , Shown below is a distribution of charges. The flux of electric field, due to these charges through the surface S is, +q, , 2, , (d) 6.32  10 CN m, , 2q, 6(4 0 ), , (d), , 25, , (c) 6.32  10 Nm C, , A charge q is located at the centre of a cube. The electric flux, through any face is, [CBSE PMT 2003], 4q, q, (a), (b), 6(4 0 ), 6(4 0 ), (c), , 21., , (1   2 ) /  0, , r 1, , (b) r 2, , (c) r 3, (d) r 4, An electric dipole is put in north-south direction in a sphere filled, with water. Which statement is correct, [MP PET 1995], (a) Electric flux is coming towards sphere, (b) Electric flux is coming out of sphere, (c) Electric flux entering into sphere and leaving the sphere are, same, (d) Water does not permit electric flux to enter into sphere, Two infinite plane parallel sheets separated by a distance d have, equal and opposite uniform charge densities  . Electric field at a, point between the sheets is, [MP PET 1999], (a) Zero, (b), , , 0, , (c), , , 2 0, , (d) Depends upon the location of the point, The electric flux for Gaussian surface A that enclose the charged, particles in free space is (given q = –14 nC, q = 78.85 nC, q = – 56, nC), [KCET 2005], 1, , 2, , (a) 10 Nm C, 3, , 2, , –1, , (b) 10 CN m, 3, , -1, , –2, , q3, , q1, q2, , 3, , Gaussian, surface A, Gaussian, surface B, , In O.P public school campus near Andhra Bank Old mangal bazar Sahjanwa Gorakhpur, Contact-9936998882,9453081912