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Which of the following charges can not be present, on an oil drop in Millikan’s experiment, , ()) 4.0 x10%C (2) 6.0 x10°"C, , (3) 10.0 x10°"C (4) all of them, , In nature, the electric charge of any system is ahways, , equal to :, , (1) half integral mukiple of the least amount of, charge, , (2) aro, , (3) square of the least amount of charge, , (4) integral multiple of the least amount of charge, , Consider a neutral conducting sphere. A positive, , point charge is placed outside the sphere. The net, , charge on the sphere is then :, , (1) negative and distributed uniformly over its, surface., , (2) negative and appears only at the point on the, sphere closest to the point charge, , (3) negative and distributed non-uniformly over its, entire surface of the sphere, , (4) zero, , Force between two identical spheres charged with, same charge is F. If 50% charge of one sphere is, transferred to the other sphere then the new force, will be :~, , 3, , 3, () GF (2 SF, , @ 3F (4) none of these, Two point charges placed at a distance 'r' in air, exert a force F. The distance at which they exert, same force when placed in a certain medium, (dielectric constant K) is —, , () 1K (2) /K, , (8) / WK (4) rR, , , , 10., , 11, , , , Two charges are placed as shown in figure. Where, should a third charge be placed so that it remains, at rest ?, , (1) 30 cm from 9e, (2) 40 cm from l6e, (3) 40 cm from 9e, (4) (1) or (2), , Two point charges +9q and +q are kept 16 cm, apart. Where should a third charge Q be placed, between them so that the system remains in, equilibrium ?, , (1) 24 cm from + 9q, , (2) 12 am from + 9q, , (3) 24 cm from + q, , (4) 12 cn from + q, , ‘Two balls carrying charges +7 C and -5 yC attract, each other with a force F. If a charge -2 yC is added, , to both, the force between them will be -(DF as, (3) 2F (4) zero, , ‘Two equal and like charges when placed 5.cm apart, experience a repulsive force of 0.144 newtons. The, magnitude of the charge in micro—coulomb will be, (02 (32, , (3) 20 (4) 12, , Two point charges of + 2 uC and + 6 wC repel, each other with a force of 12 N. if each is given, an additional charge of - 4 wC, then force will, become:, , (1) 4.N (attractive), , (2) GO N (attractive), , (3) 4 N (repulsive), , (4) 12 N (attractive), , What equal charges should to be placed on, earth and moon to neutralize their gravitational, attraction ? (mass of earth « 10** kg, massof moon, , = 107 kg), (1) 8.6 x10"C (2) 6.8 x10 C, (3 8.6 x10°C 4) 9x10°C, , a, , Oh certs seer ronme © emer eeen ce

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12., , 13., , 15., , , , ————A point charge q, exerts a force F upon another, , point charge q,. If a third charge q, be placed quite, close to the charge q, then the force that charge, q, exerts on the charge q, will be =, , yr (Q>F, , @<F (4) zero, , A charge Q is divided in two parts Q, and Q, and, these charges are placed at a distance R. There will, be maximum repulsion between them, when =, , (1) Q, = Q-q Q,=q, , 2-2a,-2, , a -29,-2, , Q, 4 Q=Q=>, , The force of repulsion between two point charges, is F, when these are 1 m apart. Now the point, charges are replaced by conducting spheres of radii, 5 cm having the charge same as that of point, charges. The distance between their centres is 1, m, then the force of replusion will —, , (1) increase (2) decrease, , (3) remain same (Ar become OE, , Two charges 4q and q are placed at a distance ¢, apart. A third charged particle Q ts placed at the, middle of them. If resultant force on q is zero then, the value of Q is —, , q @-q, , (3) 2q (4) ~ 2q, , Two similar spheres having +q and -q charges, are kept at a certain separation. F force acts, between them. If another similar sphere, having +q charge is kept in the middle of then,, it experiences a force in magnitude and, direction as :~, , (1) 2ero having no direction, , (2) 8F towards +q charge, , (3) 8F towards -q charge, , (4) 4F towards +q charge, , , , , , 17., , 18., , Four charges are placed at the circumference of, the dial of a clock as shown in figure. If the clock, has only hour hand, then the resultant force on a, positive charge q, placed at the centre, points in, the direction which 4, shows the time as =~, , (1) 4:30, , (27:30 *, , (3) 4:30, , (4) 10:30, , Two small spheres each having a charge +Q are, suspended by insulating threads of length L from a, hook. This arrangement is taken to a space where, there is no gravitational effect, then the angle, between the two threads and the tension in each, will be :, aw 10 Lae @ 90, , 1 1Q, 190. @ 18E-aan IF, Identify the wrong statement in the following :Coulomb's law correctly describes the electric force, that,, , (1) binds the electrons of an atom to it's nucleus, , (2) binds the protons and neutrons in the nucleus, of an atom, , (3) binds the atoms together to form molecules, , (4) binds the atoms and molecules together to form, solids, , , , Two charges 9e and 3e are placed at a separation r., The distance of the point where the electric, field intensity will be zero, is, , rt, aw from 9e charge, , 12 FES trom Se charge, r, , T- from 3e charge, , (0 (Pg trom 3 charge, , “a

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23., , A ting of radius R is charged uniformly with a charge, + Q. The electric field at a point on its axis at a, distance r from any point on the ring will be —, , oem OF, , @ Bey wy, , Two positive charges of 1 wC and 2 pC are placed, 1 metre apart, The value of electric field in N/C, at the mid point of the two charges will be —, , (1) 10.8 « 10* (2) 3.6 x 10*, (3) 1.8 x10* (4) 5.4 x 10*, , The electric field in a certain region is given by, E = (511. the dimensions of K are, , ()MLT“A7 (2 ML“Ta7, (3) ML*TA* (QQ M'LTAS, Figure below shows regular hexagon, with different, , charges placed at the vertices. In which of the, following cases ts the electric field at the centre, , zero ?, , ay 2) @ (a0, , Blectric field at the centre 'O’ of a semicircle of radius, ‘a’ having linear charge density ). is given as, , an, ee, , , , , , ) yea, , , , ABO, 26. A semicircular ring of radius 0.5 m is uniformly, , charged with a total charge of 1.4 x 10° C. The, electric field intensity at the centre of this ring is, , (1) zero (2) 320 V/m., (3) 64 V/m. (4) 32 V/m., , . For the given figure the direction of electric field, at A will be ;, (1) towards AL, (2) towards AY, (3) towards AX (4) towards AZ, , 1 «10°C charge is on a drop of water having, mass 10° kg. What electric field should be applied, _on the drop so that it is in the balanced condition, with its weight ?, , (2) 10 V/m upward (2). 10 V/m downward, (3) 0.1 V/m downward (4) 0.1 V/m upward, , ‘Two small identical spheres, each of mass 1 g and, carrying same charge 10°” C are suspended by, threads of equal lengths. If the distance between, the centres of the spheres is 0.3 cm in equilibrium, then the inelination of the thread with the vertical, will be —, , (2) tan"? (0.1), (3) tans? (1.5), , (2) tan (2), (4) tan"? (0.6), , 30. Two infinitely long parallel wires having linear, , charge densities 2, and 2, respectively are placed, at a distance R. The force per unit length on either, wire will be —, , oe i, ate att

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Choose the correct statement regarding electric lines, , of force —, , (1) They emerge from negative charge and, terminate at positive charge, , (2) The electric field in that region is weak where, the density of electric lines of force are more, , (3) They are in radial directions for a point charge, , (4) They have a physical existence, , A solid sphere of radius R, is charged uniformly with, a total charge Q. Then the correct expression for, electric field is (r = distance from centre) —, , (1) SO where r-< R, , 2 “D where r= R, , (3) it is zero, at all points, (4) (1) and (2) both, , Which one of the following pattem of electrostatic, lines of force is not possible ?, , A sphere of radius R and charge Q is placed inside, @ concentric imaginary sphere of radius 2R. The, flux associated with the imaginary sphere is ~, , 2 se 4Q =, OF 8 OS we, , A nonconducting solid sphere of radius R is charged, uniformly. The magnitude of the electric field due, to the sphere at a distance r from its centre , (a) increases as r increases, for r < R, , (b) decreases as r increases, for O< 1 < @, (c) decreases as r increases, for R <1 <, (d) is discontinuous at r = R, , (a,c (Qed Bab (4)b.d, , ee eee, , , , 36., , 37., , 20 iC charge is placed inside a closed surface; then, flux linked with the surface is 6. If 80 jC charge is, put inside the surface then change in flux is —, , (1) 46 (2) 5e Be (4) 84, , In @ region of space the electric field is given by, , E= 81+ 4) + 3k. The electric flux through a, surface of area of 100 units in the x-y plane is —, (1) 800 units (2) 300 units, (3) 400 units (4) 1500 units, , Electric charge ls <a ned overs long, straight wire of radius 1 mm_ . ;, The charge per cm length of the, wire is Q coulombs. A cylindrical, surface of radius 50 cm and length, 1m encloses the wire symmetrically, as shown in fig., , ‘The total flux passing through the cylindrical surface, , Q iy 1000 44 100” 4 1000, ORS (2 = ae __, , , , Gous's law is given by €, Eds = q, if net charge, , ‘enclosed by a Gaussian surface is zero then —, , (1) E must be zero on the surface, , (2) Number of incoming and outgoing electric lines, are equal, , (3) there is @ net incoming of electric lines, , (4) none, , The electric field is 100 V/m, at a distance of, , 20 cm from the centre of a dielectric sphere of, radius 10 cm. Then E at 3 cm distance from the, , centre of sphere is ~, (1) 100 V/m (2) 125 V/m, (3) 120 V/m (4) zero, , If the electric flux entering and leaving a closed, surface is $, and 6, respectively then electric charge, , inside the surface will be -, (1) (6, + @6, (2), ~ @)6,, Ste Soh., , @ % @ is

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42., , The electric field in a region of space is given by, , E=(5] +2j)N/C. Theelectric flux through an, area of 2 m* lying in the YZ plane, in S.L units is, , 4) 10 (2) 20, (3) 10 42 (4) 229, , The total flux associated with the given cube will bewhere ‘a’ is side of the cube —, , (ae = dex 9x 10°SI units, =, , , , (1) 162% x 10° Nm?/C (2) 1625 x 10° Nm?/C, , (3) 162 x 10 Nm?/C (4) 1622 x 10° Nm#/C, A point charge is placed at a distance 5, , perpendicular to the plane and above the centre, of a square of side a. The electric flux through the, , square is —, = ae eaten ett, @ = a Wie Ge