Physics Final Term 1 #1to4# - Physics - MCQ Test

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Physics Final Term 1 #1to4#

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Nov 17, 5:01 PM

400 minutes

Nov 18, 11:00 AM

700.0 marks

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Physics Final Term 1 #1to4#

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MCQ Test of Class 12, Physics Physics Final Term 1 #1to4# - Study Material

Question Text:

Question 2 : $\displaystyle P=\frac { { V }^{ 2 } }{ R }$ is applied when

Question 3 : The equivalent resistance due to series connection of $10 \Omega$ and $10 \Omega$ resistors is

Question 4 : Two non ideal batteries are connected in series. Consider the following statements (A) The equivalent emf is larger than either of the two emfs. (B)The equivalent internal resistance is smaller than either of the two internal resistances.

Question 6 : What is the power produced by an appliance marked " $240 V$, $2 A?$

Question 7 : A given resistor has the following colour scheme of the various strips on it : Brown, black, green and silver. Its value in ohm is :

Question 9 : If the temperature of a conductor is increased, its resistance will

Question 10 : An electric bulb is rated 220 volt and 100 watt, Power consumed by it when operated on 110 volt is :

Question 11 : A battery connected to a pair of parallel $30$ ohm resistor in series with a $9$ ohm resistor. The current through the $9$ ohm resistor is $0.25 A$. Find out the voltage applied to the circuit?

Question 12 : Two cylindrical rod have area of cross-section$A_1$ $A_2$. If $A_1$ is greater than $A_2$. Then which of the following is correct?

Question 13 : The smallest resistance that can be obtained by combining 10 resistors each of resistance $10 \Omega$is

Question 14 : Two wires of the same dimensions but resistivities $p_1$ and $p_2$ are connected in series.The equivalent resistivity of the combination is

Question 15 : (A) The potential difference across battery may be equal to its emf (B) The potential differences across battery may be greater than its emf (C) The potential difference across battery may be less than its emf Out of the above statements which is/are correct

Question 16 : In a potentiometer experiment, the balancing length with a cell is 560cm. When an external resistance of I0 ohms is connected in parallel to the cell the balancing length changes by 41cm. The internal resistance of the cell in ohm is 

Question 17 : If a wire is stretched , so that its length is 20% more than its initial length, the percentage increase in the resistance of the wire is

Question 19 : Assertion (A) : Meterbridge wire is made up of manganin. Reason (R) :  The temperature coeffiecient of resistance is very small for manganin.

Question 21 : The current in a circuit with an external resistance of $3.75\Omega$ is $0.5\ A$. When a resistance of $1\Omega$ is introduced into the circuit, the current becomes $0.4\ A$. The emf of the power source is

Question 23 : If a resistance is connected across the cell $e$, the balancing length will

Question 24 : The resistance of a semiconductor material (germanium or silicon)_______ with rise in temperature.

Question 26 : An electric cell does 5 joules of work in carrying 10-coulomb charge around the closed circuit. The electromotive force of the cell is :

Question 29 : In a potentiometer arrangement, a cell of emf $1.5V$ gives a balance point at $27cm$ length of wire. If the cell is replaced by another cell and balance point shifts to $54cm$, the emf of the second cell is

Question 33 : An electrical device operate at 12 A current and 120 V D.C . If it is connected with 250 V and 30 Hz AC. then power consumption:

Question 37 : In the 5 band color resistor,which color bands are considered as significant digits?

Question 38 : State whether given statement is True or False The sum of all the voltage drops around a single closed loop in a circuit is zero.

Question 39 : A primary cell has an e.m.f. of $1.5\ volt$. When short-circuited it gives a current of $3$ampere. The internal resistance of the cell is:

Question 40 : Two metallic wires of $\displaystyle 6\Omega $ and $\displaystyle 3\Omega $ are in connection. What will be the mode of connection so that to get effective resistance of $\displaystyle 2\Omega $ ?

Question 41 : A cell supplies a current of $1A$ through a resistance of $5\Omega$ and a current of $0.6A$ through a resistance of $10\Omega$. What is the internal resistance of the cell?

Question 42 : The equivalent resistance of several resistors in series is equal to the:

Question 43 : On which one of the following the emf of a cell does not depend : 

Question 44 : For a heater rated at4.4 kW; 220 V. Calculatethe current drawn by the heater.

Question 45 : Three resistors of value $2R$, $R$, and $4R$ are wired in series to a battery with a voltage $v$. Derive an expression for the current on the resistor with a value of $R$.

Question 46 : Kirchhoff's law of meshes is in accordance with law of conservation of:

Question 47 : The color coding of  earth, live and neutral wire respectively is

Question 49 : The resistance of a semiconductor material(germanium or silicon) ________with risein temperature.

Question 50 : In the metre bridge experiment of resistances, the known and unknown resistances are inter-changed. The error so removed is:

Question 52 : The potential difference in open circuit for a cell is $2.2\ V$. When a$\displaystyle 4\Omega$ resistor is connected between its two electrodes the potential difference becomes $2\ V$. The internal resistance of the cell will be

Question 53 : When a battery sends current through a resistance $R_1$ for time t,the heat produced in the resistor is Q.When the same battery sends current through another resistance$R_2$ for time t, the heat produced in $ R_2$ is again Q.The internal resistance of battery is 

Question 54 : The current carrying wire and the rod $AB$ are in the same plane. The rod moves parallel to the wire with a velocity $v$. Which one of the following statement is true about induced e.m.f. in the rod?

Question 55 : Charge passing through a conductor of cross section area $A=0.3{ m }^{ 2 }$ is given by $q=3{ t }^{ 2 }+5t+2$ in coulomb, when $t$ is in second. What is the value of drift velocity at $t=2s$? (Given, $n=2\times { { 10 }^{ 25 } }/{ { m }^{ 3 } }$)

Question 56 : Twenty four cells each of emf 1.5V and internal resistance 0.5 ohms are to be connected to a 3 ohm resistance. For maximum current through this resistance the number of rows and number of columns that you connect these cells is?

Question 57 : An electric cell of emf $E$ is connected across a copper wire of diameter $d$ and length $l$. The drift velocity of electrons in the wire is ${v}_{d}$. If the length of the wire is changed to $2l$, the new drift velocity of electrons in the copper wire will be:

Question 58 : A conductor wire, having $10^{29}$ free electrons per m$^{3}$ carries a current of $20 A$. If the cross-section of the wire is $1 mm$ $^{2}$, then the drift velocity of electrons will be of the order of:

Question 59 : A wire of uniform thickness with a resistance of $27\, \Omega$ is cut into three equal pieces and they are joined in parallel. The equivalent resistance of the parallel combination will be :

Question 60 : Two wires, each of radius r, but of different materials are connected together end to end. If the densities of charge carriers in the two wires are in the ratio 1:4,the ratio ofthe driftvelocity of electrons in the two wires will be . .

Question 61 : The resistance of Resistor A is 4 times greater than the resistance of Resistor B, if resistance A and B are connected in series then compare the following 1. Currents through these resistors ($I_A$ and $I_B$, respectively) 2. The voltage drops across them ($V_A$ and $V_B$, respectively)

Question 62 : When a resistor of $11 \Omega$ is connected in series with a electric cell. The current following in it is $0.5 A$. Instead when a resistor of $5 \Omega$ is connected to the same electric cell in series, the current increases by $0.4 A$. The internal resistance of the cell is

Question 63 : Three resistances of 2, 3 and 5 $\Omega$ are connected in parallel to a lay battery 10V with negligible internal resistance. The potential difference across the $3 \Omega$ resistance will be

Question 65 : Threeequal resistors connected in series acrossa source of e.m.f. together dissipate 10 watt ofpower. What would be the power dissipated if thesame resistors are connected in parallel across the same source of e.m.f.?

Question 66 : The number of dry cells, each of e.m.f. $1.5$ volts and internal resistance $0.5\ ohm$ that must be joined in series with a resistance of $20\ ohm$ so as to send a current of $0.6$ ampere through the circuit is

Question 67 : n identical resistors each of resistance r when connected in parallel, have a total resistance R. When these resistors are connected in series, then effective resistance in terms of R is:

Question 68 : Anexternal resistance R is connected to a cell ofinternal resistance r. The largest amount ofcurrent flows in the external resistance, when

Question 70 : Two bulbs of $100 W$ and $200 W$ working at $220$ volt are joined in series with 220 volt supply. Total power consumed wll be approximately.

Question 72 : Write true or false for the following statements : Resistance of a conductor increases with the increase in temperature.

Question 73 : $12$ cells each of e.m.f $2V$ are connected in series among them, if $3$ cells are connected wrongly. Then be effective e.m.f. of the combination is:

Question 74 : A d.c. main supply of e.m.f. 220 V is connected across a storage battery of e.m.f 200 V through a resistance of $1\Omega.$ The battery terminals are connected to an external resistance 'R'. The minimum value of 'R', so that a current passes through the battery to charge it is :

Question 75 : When a resistance of 2 ohms is connected across the terminals of a cell, the current is 0.5 A. When the resistanceis increased to 5 ohms, the current becomes 0.25 A. The e.m.f. of the cell is :-

Question 76 : The daniel cell is balanced on $125 cm$ length of a potentiometer. Now, the cell is short circuited by a resistance of $2\Omega $ and the balance is obtained at $100 cm$. The internal resistance of the daniel cell is :

Question 77 : An electric current is passed through a circuit containing two wires of the same material, connected in parallel. If the lengths and radii of the wires are in the ratio of $4/3$ and $2/3$, then the ratioof the currents passing through the wire will be

Question 79 : Assertion: The e.m.f. of the driver cell in the potentiometer experiment should be greater than the e.m.f. of the cell to be determined. Reason: The fall of potential across the potentiometer wire should not be less than the e.m.f. of the cell to be determined.

Question 80 : The unit of electrical power is watt and $1$ watt is the same as ___________.

Question 81 : Read the following statements carefully: Y: The resistivity of a semiconductor decreases with the increase of temperature. Z: In a conduction solid, rate of collision between free electrons and ions increases with the increase of temperature.Select the correct statement(s) from the following.

Question 82 : Two cells of internal resistances $r_1$ and $r_2$ and of same emf are connected in series, across a resistor of resistance R. If the terminal potential difference across the cells of internal resistance $r_1$ is zero, then the value of R is?

Question 83 : E.m.f. device X does not have internal resistance . what is its e.m.f. ?

Question 84 : The resistance of one ohm is very approximately equal to  that of a column of mercury $1.06 m$ long and of uniform cross-section of one hundredth of $1\ cm^2$. Find the resistivity of mercury.

Question 85 : An electric current of $16A$ exists in a metal wire of cross section ${ 10 }^{ -6 }{ m }^{ 2 }$ and length $1m$. Assuming one free electron per atom. The drift speed of the free electrons in the wire will be: (Density of metal $=5\times { 10 }^{  }kg/{ m }^{ 3 }$, atomic weight $=60$)

Question 86 : In a potentiometer, the balance length with standard cadmium cell is 509 cm. The emf of a cell which when connected in the place of the standard cell gave a balanced length of 750 cm is (emf of the standard cell is 1.018V):

Question 87 : The ratio of the drifty velocity $v_d$ and r.m.s. velocity of electrons is

Question 88 : Three wires having resistances  $1\Omega , 2\Omega$ and $ 6\Omega $ are joined in parallel across a battery. If a current 0.1A flows through $6\Omega $ resistor, the total current drawn by the combination is:

Question 89 : The momentum acquired by all free electrons in a wire a length l when a current of i amp starts to flow is

Question 90 : Two non-ideal batteries are connected in series. Consider the following statements: (A) The equivalent emf is larger than either of the two emfs. (B) The equivalent internal resistance is smaller than either of the two internal resistances

Question 91 : For ohmic conductor the drift velocity $v_d$ and the electric field applied across it are related as :

Question 92 : The inductance of a coil is $L = 10 H$ and resistance $R = 5 \Omega$. If applied voltage of battery is $10 V$ and it switches off in $1$ millisecond, find induced electromotive force of inductor.

Question 93 : Copper contains $8.4\times { 10 }^{ 28 }$ free $electrons/{m}^{3}$. A copper wire of cross-sectional area $7.4\times { 10 }^{ -7 }{ m }^{ 2 }$ carries a current of $1$ A. The electron drifts speed is approximately :

Question 96 : Drift velocity $v_a$ varies with the intensity of elastic filed as per the relation:

Question 97 : An electric kettle consumes 1 kW of electric power when operated at 220 V. A fuse wire of what rating must be used for it?

Question 98 : $10$ wires (same length, same area, same material) are connected in parallel and each has $1\Omega$ resistance, then the equivalent resistancewill be

Question 99 : A battery of emf  $ \in $ and internal resistance r is used in a circuit with variable external resistance R .The value of R for which power consumed in it is maximum will be.

Question 100 : In a potentiometer of wire length $l$, a cell of emf V is balanced at a length $\dfrac{l}{3}$ from the positive of the wire. For another cell of emf $1.5 V$, the balancing length becomes

Question 101 : When a battery sends current through the resistances $R_1$ and $R_2R$, the internal resistance of battery is :

Question 102 : The colour code of a carbon resistor is, Brown, Black, Brown and Red. The value of the resistor is?

Question 103 : Copper has one conduction electron per atom. Its density is $8.89{ g }/{ m^3}$ and its atomic mass is 63.54 g/mol. lf a copper wire of diameter 1.0 mm carries a current of 2.0 A. What is the drift speed of the electrons in the wire?

Question 104 : If an alternate current main supply is given to be $220 \ V$. What would be the average electro motive force during a positive half cycle:

Question 105 : Assertion: STATEMENT-1 : The current density $\vec{J}$ at any point in ohmic resistor is in direction of electric field $\vec{E}$ at that point. Reason: STATEMENT-2 : A point charge when released from rest in a region having only electrostatic field always moves along electric lines of force.

Question 106 : What will be the nature of charge on the metal paper clip of electroscope when a positively charged body is brought in contact with it?

Question 107 : If $\oint _{ s }^{  }{ \overrightarrow { E } .\overrightarrow { d } s } =0$ over surface, then

Question 110 : Why is electrical wiring usually covered with a layer of plastic?

Question 111 : A negatively charged particle is situated on a straight line joining two other stationary particles each having charge $ +q$. The direction of the motion of the negatively charged particle will depend on:

Question 112 : A point charge ${q_1} =  - 5.8\mu C$ is held stationary at the origin . A second point charge ${q_2} =  + 4.3\mu C$ moves from the point $(0.26m,0,0)$ to $(0.38m,0,0)$.How much work is done by the electric force on {q_2}.

Question 113 : fast neutrons may most easily be slowed down by which one of the following methods?

Question 116 : Calculate the magnitude of the force between two electrons which are 
separated by a distance of $10^{-10}m$. If the magnitude of the charge
 is $10^{-19}C$ and Coulomb constant is $10^{10}N\;m^{2}/C^{2}$.

Question 121 : A particle A has charge +q and a particle B has charge +4q. each having the same m . allowed to fall from rest through the same electric potential difference. the ratio of the speed of A to that of B will e

Question 122 : Deuteron and $\alpha$-particle are put $1{A}^{o}$ apart in air. Magnitude of intensity of electric field due to deuteron of $\alpha$-particle is $(N/C)$

Question 124 : A charge $q_1$ exerts a force of $45N$ on a charge of $q_{2}=10^{-5} C$ located at a point $0.2m$ from $q_{1}$. The magnitude of $q_{1}$ is

Question 125 : Assertion: Gaussian surface is considered carefully. Reason: The point where electric field to be calculated should be within the surface.

Question 126 : A plane area of $100\ {cm}^{2}$ is placed in uniform electric field of $100\ N/C$ such that the angle between area vector and electric field is $60^o$. The electric flux over the surface is

Question 130 : What is the ratio of electric field intensity at distance $5$ cm to that at $10$ cm from a point charge $Q$ in air?

Question 132 : If $10$ million electrons are removed from a neutral body, then the charge on the body is :

Question 133 : A gold leaf electroscope is given a positive charge so that its leaves diverge. How is the divergence of leaves affected, when a negatively charged rod is brought near its disc?

Question 134 : Fill in the blank.$1$ Coulomb of charge contains_______number of electrons.

Question 136 : The process of charging a conductor from a chargedbody without touching them together is calledinduction

Question 137 : Two spheres of radii 2 cm and 3 cm have equal surface charge density. Calculate the ratio of their charges.

Question 138 : You are provided with a negatively charged gold leaf electroscope. State and explain what happens when an ebonite rod rubbed with fur is brought near the disc of electroscope.

Question 139 : In Coulomb's law, the constant of proportionality K has the units $Nm^2/C^2$ then the magnitude of K in air is :

Question 140 : What is the angle between the electric dipole moment and the electric field due to it on the axial line?

Question 141 : State whether the following statements are True or False. If E=0, at all points of a closed surface, The electric flux through the surface is zero.

Question 142 : Which of the following devicesis used to detect the presences of a charge on a body?

Question 144 : The electric flux over a sphere of radius $1 m$ is $\phi$. If radius of the sphere were doubled without changing the charge enclosed, electric flux would become

Question 146 : A charged particle is accelerated by a potential of 200V. If its velocity is $8.4\times 10^8m/s$, then value of e/m for that particle in $C/kg$  is:

Question 147 : Electric field at a distance r from infinitely long conducting sheet is proportional to :

Question 148 : If the flux of the electric field through a closed surface is zero:

Question 149 : The ratio of electric force between two electrons to two protons separated by the same distance in air is

Question 150 : A force ‘F’ is acting between two charges in air. If the space between them be completely filled with a medium $K=4$, the force will be :

Question 151 : A $1\ \mu A$ beam of proton with a cross-sectional area of $0.5\ sq. mm$ is moving with a velocity of $3\times 10^4\ ms^{-1}$. Then charge density of beam is

Question 154 : Materials which allow larger currents to flow through them are called :

Question 156 : Assertion: The flux crossing through a closed surfaces is independent of the location of enclosed charge. Reason: Upon the displacement of charges with in a closed surface, the $\vec {E }$ at any point on surface does not change.

Question 157 : A particle of mass m and charge $q$ is thrown in a region where uniform gravitational field and electric field are present. The path of particle :

Question 158 : Two point charges $+4e$ and $+e$ are $x$ distance apart. The distance of charge $q$ from charge $+e$ so that it is in equilibrium is :

Question 159 : 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 :

Question 160 : Two identical charged spheres suspended from a common distance $d(d < < 1)$ apart because of their mutual repulsion. The charged begin to leak from both the spheres at a constant rate. As a result, the spheres approach each other with a velocity $v$. Then $v$ varies as a function of the distance $x$ between the spheres, as

Question 162 : If the coulombian force acting between two protons separated by a distance r is F, what would be the force acting between two $\alpha-$particles separated by a distance 2r ?

Question 163 : A charge of $-30 \mu C$ is placed at 50 cm from another charge of $+25\mu C$ is vacuum. The force between them is:

Question 164 : Surface density of charge on a sphere of radius $R$ in terms of electricity intensity $E$ at a distance $r$ in free space is ________.($\epsilon_0$= permittivity of free space)

Question 165 : A point charge is brought in an electric field. The electricfield at a nearby point

Question 166 : At the centre of a cubical box $+ Q$ charge is placed. The value of total flux that is coming out of each face is :

Question 167 : Two point charges $(+e)$ and $(-e)$ are kept inside a large metallic cube without touching its sides. Electric flux emerging out of the cube is?

Question 168 : When a polythene piece is rubbed with wool, it acquires negative charge. 

Question 169 : Charges of $1 \mu C$ and $10\mu C$ are placed and held$0.1m$ apart. What will be the force they exert on each other?

Question 170 : Two particles having charges $q_1$ and $q_2$ when kept at a certain distance, exert a force F on each other. If the distance between the two charges is reduced to half then the force exerted on each other would be:

Question 171 : A charge q is distributed over two spheres of radii R and r such that their surface densities are equal. What is the ratio of the charges on the spheres?

Question 172 : Two charges are placed a certain distance apart in air. If a glass slab is introduced between them, the force between them will

Question 173 : A long string with a charge of $\lambda $ per unit length passes through an imaginary cube of edge length $a$. The maximum flux of the electric field through the cube will be:

Question 175 : Two identically charged metal spheres A and B experience a force of $2 \times 10^{-5}$ Newton of repulsive nature. Another, similar uncharged metal spheres C is brought near A and after contact with A it is separated and now placed midway between A and B. The total force on this new spheres C in Newton is:

Question 176 : A laser beam of pulse power ${ 10 }^{ 12 }W$ is focussed on an object of area ${ 10 }^{ -4 }{ cm }^{ 2 }$. The energy flux in $W/{ cm }^{ 2 }$ at the point of focus is

Question 177 : The electric flux entering a closed surface is $2000 Vm$ and the flux coming out of the closed surface is $1000 Vm$. Then, the net charge enclosed inside the surface is :

Question 178 : If the electric flux entering and leaving an enclosed surface respectively are $\phi_1$ and $\phi_2$, the electric charge inside the surface will be :

Question 179 : A charge +Q is located in space at point $(x=1 m,y=10m, z=5m)$. What is the total electric flux that passes through the $y-z$ plane?

Question 180 : A charge of $1 \mu C$ is divided into two parts such that their charges are in the ratio of $2 : 3$. These two charges are kept at a distance $1 m$ apart in vacuum. Then, the electric force between them (in N) is:

Question 182 : State whether the given statement is True or False :Gauss' law is useful for the calculation of electrostatic field when the system doesn't possess any symmetry.

Question 183 : If the object is not grounded while performing electrostatic induction, the nearby charge will

Question 185 : If a charge q is placed at the centre of the line joiningtwo equal charges Q such that the system is inequilibrium then the value of $q$ is :

Question 186 : Position vectors of two point charges of $1nC$ each are $(1,1,-1)$m and $(2,3,1)$m respectively. Magnitude of electric force acting between them is ___N.

Question 188 : A large, metallic, spherical shell has no net charge. It is supported on an insulating stand and has a small hole at the top. A small tack with charge Q is lowered on a silk thread through the hole into the interior ofthe shell.What is the charge on theouter surface of the shell?

Question 189 : A wire havinga linear density $0.10 kg/m$ is kept under a tension $490 N$ it is observed that it resonates at a frequency of $400 Hz$ and the next frequency $450 Hz$. The length of the wire is

Question 190 : 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 :

Question 191 : A charge of $10$ $units$ is divided so that force between the two charges is maximum when placed $2$ $cm$ apart. The two charges are:

Question 192 : Awire of linear charge density $\lambda$ passes through a cuboid of length $\ell$, breadth $b$ and height $h\ (\ell>b>h)$ in such a manner that flux through the cuboid is maximum. The position of the wire is now changed, so that the flux through the cuboid is minimum. The ratio of maximum flux to minimum flux will be :

Question 193 : A circular plane sheet of radius $10cm$ is placed in a uniform electric field of $5{ \times 10 }^{ 5 }N\quad { C }^{ -1 }$, making an angle of ${60}^{o}$ with field. The electric flux through the sheet is

Question 194 : A glass rod when rubbed with silk cloth acquires acharge $1.6 \times 10^{-13} C$. What is the charge on the silkcloth?

Question 195 : Two equally charged identical metal spheres A and B repel each other with a force F. Another identical uncharged sphere C is touched to A and then placed midway between A and B. The net force on C is in the direction:

Question 196 : A point charge $q$ is placed at a point on the axis of a non-conducting circular plate of radius $r$ at a distance $R (R >> r)$ from its center. The electric flux associated with the plate is :

Question 197 : Charges $Q_1$ and $Q_2$ are placed inside and outside respectively of an uncharged conducting shell. Their seperation is r.

Question 198 : A particle of mass m and charge -q moves diametrically through a uniformly charged sphere of radius R with total charge Q. The angular frequency of the particle's simple harmonic motion, if its amplitude < R, is given by :

Question 199 : Assertion: STATEMENT-1 : In a region where uniform electric field exists, the net charge within volume of any size is zero. Reason: STATEMENT-2 : The electric flux within any closed surface in a region of uniform electric field is zero.

Question 200 : Charges $Q_1$ and $Q_2$ lie inside and outside respectively of a closed surface S. Let E be the field at any point on S and $\psi$ be the flux of E over S.

Question 201 : The radii of two conducting sphere are $ a $ and $ b $. They are charged by equal charge density. What would be the ratio of the electric field intensities at their surface?

Question 202 : A point charge $Q(C)$ is placed at the origin. Find the electric flux of which an area $4\pi\ m^2$ on a concentric spherical shell of radius $R$

Question 203 : A sphere of radius R carries charge such that its volume charge density is proportional to the square of the distance from the center. What is the ratio of the magnitude of the electric field at distance 2R from the center to the magnitude of the electric field at a distance of R/2 from the center?

Question 204 : Let there be a spherically symmetric charge distribution with charge density varying as $\displaystyle \mathrm{p}(\mathrm{r})=\mathrm{p}_{0}(\frac{5}{4}-\frac{\mathrm{r}}{\mathrm{R}})$ upto $\mathrm{r}=\mathrm{R}$, and $\mathrm{p}(\mathrm{r})=0$ for $\mathrm{r}>\mathrm{R}$, where $\mathrm{r}$ is the distance from the origin. The electric field at a distance $\mathrm{r}(\mathrm{r}<\mathrm{R})$ from the origin is given by :

Question 205 : Two thin rods of linear charge density $\lambda$ Cm$^{-1}$ are separated by a distance d metre. The force on unit length of each rod is :

Question 206 : To make the magnetic field radial in a moving coil galvanometer:-

Question 207 : The magnitude of the magnetic field inside along solenoid is increased by

Question 209 : A beam of electrons passes undeflected through mutually perpendicular electric and magnetic fields. It the electric field is switched off, and the same magnetic field is maintained, the electrons move:

Question 210 : When a solenoid is activated, the force that moves the plunger is

Question 211 : Why does a current carrying freely suspended solenoid rest along a particular direction?

Question 215 : The magnetic field normal to a coil of 40 turns area $ 3 cm^2 $ is B = (250 - 0.6t) millitesla. The emf induced in the coil will be

Question 216 : A moving coil type of galvanometer is basedupon the principle that

Question 218 : The sensitivity of a moving coil galvanometer increases with the decrease in

Question 219 : In a moving cell galvanometer, we use a radial magnetic field so that the galvanometer scale is

Question 220 : In ballistic galvanometer, the frame on which the coil is wound is non-metallic to:

Question 221 : In cyclotron, for a given magnet, radius of the semicircle traced by positive ion is directly proportional to ($v=$ velocity of positive ion).

Question 222 : Complete the following statements with an appropriate word / term to be filled in the blank space(s). Magnetic field lines emerge from the _________ pole of a solenoid or a permanent magnet.

Question 223 : Complete the following sentenceA current carrying solenoid behaves like a $\underline{          }$. 

Question 224 : Two straight parallel wires carrying current in the opposite directions repel each other, because of

Question 225 : Assertion: The coil is bound over the metallic frame in moving coil galvanometer. Reason: The metallic frame helps in making steady deflection without any oscillation.

Question 226 : In cyclotron, radius of circular path traced by positive ions is ____________.

Question 227 : Which of the following is likely to have the largest resistance?

Question 229 : A solenoid with a soft iron core is called a _____.

Question 232 : Assertion: The magnetic field at the ends of a very long current carrying solenoid is half of that at the centre. Reason: If the solenoid is sufficiently long, the field within it is uniform.

Question 233 : The gyro-magnetic ratio of an electron in an H-atom, according to Bohr's model, is

Question 238 : The restoring couple in the moving coil galvanometer is due to

Question 240 : Best method to increase the sensitivity of the moving coil galvanometer is to decrease

Question 241 : If a galvanometer is shunted then among the following not true one is

Question 243 : A charged particle with charge $q$enters a regionof constant uniform and mutually orthogonal fields$\vec{E}$ and $\vec{B}$with a velocity $\vec{v}$ perpendicular to both$\vec{E}$ and $\vec{B}$ and comes out without any change in magnitude and direction of $\vec{v}$. Then,

Question 244 : An 8 cm long wire carrying a current of 10 A is placed inside a solenoid perpendicular to its axis. If the magnetic field inside the solenoid is 0.3 T, then magnetic force on the wire is

Question 245 : A circular coil of wire is connected to a battery of negligible internal resistance and has magnetic induction $B$ at its centre. If the coil is unwound and rewound to have double the number of turns, and is connected to the same battery, then the magnetic induction at the center is :

Question 246 : A coil of area $A$, turns $N$ and carrying current $i$ is placed with its face parallel to the lines of magnetic induction $B$. The work done in rotating the coil through an angle of $180^{0}$ is

Question 247 : A long solenoid has magnetic field strength of $3.14\times 10^{-2}\ T$ inside it when a current of $5\ A$  passes through it. The number of turns in $1\ m$ length of the solenoid is

Question 248 : How much length of a very wire is required to obtain a solenoid of length $I_0$ and inductance L :

Question 249 :  A device used for measuring small currents due to changing magnetic field is known as:

Question 250 : A light body is hanging at the lower end of a vertical spring. On passing current in the spring, the body

Question 251 : Two streams of electrons are moving parallel to each other in the same direction. They_____

Question 253 : A current of $10^{-7}$ ampere produces 50 division deflection in a galvanometer. Then its figure of merit will be

Question 254 : A particle specified charge $(q/m)$ is projected from the origin of coordinates with initial velocity $[u\hat{i} - v\hat{j}].$ Uniform electric magnetic fields exists in the region along the +y direction, of magnitude $E$ and $B$. The particle will definitely return to the origin once if.

Question 256 : Assertion: The earths magnetic field does not affect the working of a moving coil galvanometer. Reason: Earths magnetic field is very weak

Question 257 : A charged particle with a velocity $2\times 10^3ms^{-1}$ passes undeflected through electric field and magnetic fields in mutually perpendicular directions. The magnetic field is $1.5$T. The magnitude of electric field will be.

Question 258 : A wire carrying a current of 140 ampere is bent into the form of a circle of radius 6 cm. The flux density at a distance of 8 cm on the axis passing through the centre of the coil and perpendicular to its plane is _______ wb / $m^{2}$:

Question 259 : " On flowing current in a conducting wire the magnetic field produces around it". It is a law of

Question 260 : A charge particle is moving in a uniform magnetic field in a circular path. Radius of circular path is $R$. When energy of particle is doubled, then new radius will be

Question 261 : A solenoid is 1.5$m$ long and its inner diameter is 4.0$ { cm }$ . It has 3 layers of winding's of 1000 turns each and carries a current of 2.0 amperes.The magnetic flux for a cross-section of thesolenoid is nearly.

Question 262 : A current $i$ ampere flows along an infinitely long straight thin walled tube, then the magnetic induction at any point inside the tube is

Question 263 : Assertion: Path of a charged particle in uniform magnetic field can't be a parabola. Reason: For parabolic path acceleration should be constant.

Question 264 : The radius of curvature of the path of the charges particles in a uniform magnetic field is directly proportional to

Question 265 : A vertical rectangular coil of sides $5 cm \times 2 cm$ has $10$ turns and carries a current of $2A$. The torque(couple) on the coil when it is placed in a uniform horizontal magnetic field of $0.1T$ with its plane perpendicular to the field is

Question 266 : A particle of mass $m$ and charge $q$ enters a magnetic field $B$ perpendicular with a velocity $v$. The radius of the circular path described by it will be

Question 267 : Sensitivity of moving coil galvanometer is '$s$'. If a shunt of $\left (\dfrac {1}{8}\right )^{th}$ of the resistance of galvanometer is connected to moving coil galvanometer, its sensitivity becomes:

Question 268 : If a galvanometer has full scale deflection current $I_{G}$ and resistance $G$. A shunt resistance $R_{A}$ is used to convert it into an ammeter of range $I_{0}$ and a resistance $R_{V}$ is connected in series to convert it into a voltmeter of range $V_{0}$ such that $V_{0} = I_{0}G$ then $R_{A} R_{V}$ and $\dfrac {R_{A}}{R_{V}}$ respectively are

Question 270 : An electron is moving on a circular path of radius $r$ with speed $v$ in a transverse magnetic field $B$. $e/m$ for it will be

Question 271 : A positive charge moves with constant velocity to the right through both a magnetic and electrostatic field. Which of the following conditions would allow for this to happen? Ignore effects from the force of gravity.

Question 272 : When two infinitely long parallel wires separated by a distance of $1m$, each carry a current of $3A$, the force in newton/metre length experienced by each will be, (given $\mu _{0}=4\pi \times 10^{-7}$ S.I. Units).

Question 273 : Phosphor-bronze wire is used for suspension in a moving coil galvanometer, because it has.

Question 274 : A tightly-wound long solenoid has n turns per unit length,radius r and carries a current $i$. A particle having charge q and mass m is projected from a point on the axis in the direction perpendicular to the axis.The maximum speed for which particle does not strike the solenoid will be

Question 275 : The expression for the torque acting on a coil having area of cross-section $A$, number of turns $n$, placed in a magnetic field of strength $B$, making an angle $\theta$ with the normal to the plane of the coil, when a current $i$ is flowing in it, will be

Question 276 : If a proton, deutron and $\alpha-$particle or being accelerated by the same potential difference entersperpendicular to the magnetic field, then the ratio of their kinetic energy is

Question 277 : This section contains multiple choice questions. Each  question has 4 choices (a), (b), (c) and (d ) out of which ONE OR MORE may be correct. A proton moving with a constant velocity passes through a region of space without any change in its velocity. If E and B represent the electric and magnetic fields respectively, Identify which of the following options can be true for the space.

Question 279 : The torque on a bar magnet due to the earth's magnetic field ismaximum when the axis of the magnet is

Question 280 : A moving coil galvanometer has 48 turns and area of coil is $\displaystyle 4\times { 10 }^{ -2 }{ m }^{ 2 }$. If the magnetic field is 0.2T, then to increase the current sensitivity by 25% without changing area (A) and field (B) the number of turns should become :

Question 281 : A helium nucleus completes one revolution in acircular path of radius 0.8m in 2 seconds. Themagnetic induction at the centre of the path willbe

Question 282 : A proton, a deutron and an $\alpha-$particle are accelerated through the same potential difference and then they enter a uniform normal magnetic field. If the radius of circular path of proton is $8 cm$ then the radius of circular path of deutron will be

Question 283 : Two long straight wires of length $l$ lie parallel toone another and carry currents opposite to oneanother of magnitudes $i_{1}$ and $i_{2}$ respectively. Theforce experienced by each of the straight wires is( r is the distance of their separation)

Question 284 : The magnetic field due to a current carrying circular loop of radius 3 cm at a point on the axis at a distance of 4 cm from the centre is 54 $\mu \mathrm{T}$. What will be its value at the centre of the loop?

Question 285 : A charge $e$ moves round a circle of radius $r$ with a uniform speed $v$. The magnitude of the magnetic induction at the centre of the circle is

Question 286 : The magnetic field inside a toroid is $B$. If $n$ are the number of turns in unit length of the toroid is $n$ and $I$ current is flowing in the toroid then magnetic field outside the toroid will be:

Question 287 : A wire in the form of a circular loop of one turn carrying a current produces a magnetic field $B$ at the centre. If the same wire is looped into a coil of two turns and carries the same current, the new value of magnetic induction at the centre is:

Question 288 : A proton of mass $m$ and charge $q$ is moving in a plane with kinetic energy $E$. If there exists a uniform magnetic field $B$, perpendicular to the plane of the motion the portion will move in a circular path of radius

Question 289 : Current 'i' is carried in a wire of length L. If the wire is turned into circular coil, the maximum magnitude of torque in a given magnetic field B will be

Question 290 : A solenoid has core of a material with relative permeability $500$ and its windings carry a current of $1$A. The number of turns of the solenoid is $500$ per metre. The magnetization of the material is nearly.

Question 291 : A wire is wound on a long rod of material of relative permeability $\mu_r = 4000$ to make a solenoid. If the current through the wire is $5 A$ and number of turns per length is $1000$ per meter, then the magnetic field inside the solenoid is:

Question 292 : The percentage increase in magnetic field B when the space within a current carrying toroid is filled with aluminium $(X = 2.1 \times 10^{-5})$ is

Question 293 : An electron and a proton of equal momentum enter a uniform magnetic field normal to the lines of force. If the radii of circular paths be $r_e$ and $r_p$, respectively, then

Question 295 : A stream of protons and $\alpha$-particles of equal momenta enter a uniform magnetic field perpendicularly.The radii of their orbits are in the ratio

Question 296 : Consider the following statements: A) Time period of a charged particle in uniformmagnetic field is independent of K.E of the particle B) Time period of a charged particle in uniformmagnetic field depends on the angle betweenvelocity and magnetic field C) Time period of a charged particle in uniformmagnetic field is inversely proportional to specificcharge

Question 297 : A proton moving with a constant velocity passes through a region of space with out change in its velocity. If E and B represent the electric and magnetic fields respectively, this region may have 

Question 298 : Two wires carry currents of  $100\  A$ and  $200\  A$ respectively and they repel each other with a force of  $0.4\  N/m$. The distance between them will be :

Question 299 : A circular coil of 25 turns and radius 12 cm is placed in a uniform magnetic field of 0.5 T normal to the plane of the coil. If the current in the coil is 6 A then total torque acting on the coil is

Question 300 : If the distance as well as the current in each of two parallel current carrying wires is doubled, the force per unit length acting between them becomes

Question 301 : A proton is moving with velocity ${10}^{4}m/s$ parallel to the magentic field of intensity 5 tesla.The force on the proton is

Question 302 : In a cyclotron the AC potential difference is V and frequency is f. The increase in energy of particle of charge q in one revolution will be

Question 304 : A proton and alpha particle both enter a region of uniform magnetic field B, moving at right angles to the field B. If the radius of circular orbits for both the particles is equal and the kinetic energy acquired by proton is 1 MeV, the energy acquired by the alpha particle will be:

Question 305 : A circular loop of radius $1 m$ carries an electric current. Let $P$ and $Q$ be two points on the axis of the loop at distance $1 m$ and $7 m$ respectively from the center. If the magnetic field at P due to the current is $125 \ mT$, then the magnetic field at $Q$ will be about :

Question 306 : A circular current carrying coil has a radius $R$. The distance from the centre of the coil on the axis where the magnetic induction will be $\dfrac{1}{8}^{th}$ to its value at the centre of the coil, is :

Question 307 : What would be the speed of second particle so that both particles meet again and again after a regular interval of time, which should be minimum?

Question 308 : An electron whose e/m is $1.76\times 10^{11}$ c/kg enter a region where there is a uniform magnetic field of induction $2\times 10^{-3}$ tesla with a velocity of $3\times 10^{6}$ m/sec in a direction making an angle of $45^{0}$ with the field. The pitch of its helical path in the region is:

Question 309 : A current of i ampere is flowing in an equilateral triangle of side a. The magnetic induction at the centroid will be?

Question 310 : Three particles, an electron $(e),$ a proton $(p)$ and a helium atom $(He)$ are moving in circular paths with constant speeds in the $x-y$ plane in a region where a uniform magnetic field $B$ exists along z-axis. The times taken by $e, p$ and $He$ inside the field to complete one revolution are $t_e, t_p$ and $t_{He}$ respectively. Then :

Question 311 : When air is replaced by a dielectric medium of constant $K$, the capacity of the condenser:

Question 312 : When a thin mica sheet is placed between the plates of a condenser then the amount of charge, so compared to its previous value, on its plates will become:

Question 313 : Which material sheet should be placed between the plates of a parallel plate condenser in order to increase its capacitance ?

Question 314 : When a dielectric is introduced between the plates of a condenser, the capacity of condenser :

Question 315 : A sheet of aluminium foil of negligible thickness is introduced between the plates of a capacitor. The capacitance of the capacitor :

Question 317 : A parallel plate capacitor is charged. If the plates are pulled apart

Question 318 : The capacity of a parallel plate capacitor with no dielectric substance but with a separation of $0.4cm$ is $2\mu F$. If the separation is reduced to half and it is filled with a dielectric substance of value $2.8$, then the final capacity of the capacitor is

Question 319 : A capacitor consists of two metal plates each$10{\text{ }}cm$ by$20{\text{ }}cm;$ they are separated by a$2.0{\text{ }}mm$ thick insulator with dielectric constant$4.1$ and dielectric strength 6.0107 V/m. What is the capacitance in$pF\left( {{{10}^{ - 12}}F} \right)?$

Question 320 : A parallel plate capacitor C is charged by connecting it to a battery using a switch S as shown in the figure, Now S is opened and the plate separation is then increased. As a result:

Question 321 : Displacement current goes through the gap between the plates of a capacitor when the charge of the capacitor

Question 322 : If on combining two charged bodies, the current does not flow then :

Question 323 : A parallel plate capacitor is charged and then isolated. What is the effect of increasing the plate separation on charge, potential, capacitance, respectively?

Question 324 : In a parallel plate condenser if the distance between the plates is made half and the dielectric constant is doubled, then the capacity increases by a factor:

Question 325 : If the inductance and capacitance are both doubled in L-C-R circuit, the resonant frequency of the circuit will :

Question 327 : The capacity of a parallel plate condenser consisting of two plates each of $10\ cm^2$, separated by a distance of $2\ mm$ is:(Take air as the medium between the plates)

Question 328 : Two parallel plate air capacitors have the same separation. The plates of the first are squares of side 10 cm. The plates of the second are squares of side 20 cm. The ratio of their capacitance is :

Question 329 : A capacitor of capacitance $2\ \mu F$ is charged to a voltage of $6\  V$. The charge on its plates is:

Question 330 : Force acting upon a charged particle kept between the plates of a charged condenser is F.If one of the plates of the condenser is removed,force acting on the same particle will become

Question 331 : Select correct Statements : a) Charge cannot be isolatedb) Repulsion is the sure test to know the presence of chargec) Waxed paper is dielectric in paper capacitord) Variable capacitor is used in tuning circuits in radio

Question 332 : Three capacitors $2\mu F, 3\mu F$ and $5\mu F$ are connected in parallel. The capacitance of the combination:

Question 333 : There are $10$ condensers each of capacity $5\; \mu F$. The ratio of minimum to maximum capacity obtained from these condensers will be :

Question 334 : To obtain $3 \mu F$ capacity from three capacitors of $2 \mu F$ each, they will be arranged as follows:

Question 335 : From a supply of identical capacitors rated $8\ \mu F, 250\ V$, the minimum number of capacitors required to form a composite $16\ \mu F, 1000\ V$ capacitor is:

Question 336 : Two capacitors of $1\mu F$ and $2\mu F$ are connected in series and this combination is changed upto a potential difference of $120$ volt. What will be the potential difference across $1 \mu F$ capacitor:

Question 337 : Four capacitors of equal capacitance have an equivalent capacitance ${ C }_{ 1 }$ when connected in series and an equivalent capacitance ${ C }_{ 2 }$ when connected in parallel. The ratio $\dfrac { { C }_{ 1 } }{ { C }_{ 2 } } $ is

Question 338 : For capacitors in the series combination, the total capacitance C is given by

Question 339 : Find the total capacitance for three capacitors of $10$f,$15$f and $35$f in parallel with each other?

Question 340 : Two capacitors of capacity $C_1$ and $C_2$ are connected in parallel, then the equivalent capacity is:

Question 341 : In a charged capacitor the energy is stored in:

Question 342 : Two parallel-plate of capacitor have charges +Q and -Q and potential difference $\triangle V$ due to charging, Now the capacitor is disconnected then the potential difference and the stored electrical potential energy is:

Question 343 : A potential difference of $\Delta V$exists between two plates of a parallel-plate capacitor with capacitance C . A dielectric with a dielectric constant of kis then placed between the plates of the capacitor. What is the energy stored in the capacitor?

Question 344 : If the charge on the condenser of $10\mu F$ is doubled, then the energy stored in it becomes ____________.

Question 345 : A capacitor having capacity of $2.0\mu F$ is charged to $200\ V$ and then the plates of the capacitors are connected to a resistance wire. The heat produced in joule will be :

Question 346 : The capacity of a condenser is 20$\mu F$ $\displaystyle $ and the potential is 20 V. The energy released an discharging it fully will be

Question 347 : A $2 \mu F$ capacitor is charged to $100 V$ and then its plates are connected by a conducting wire, the heat produced is :

Question 348 : The energy stored in a capacitor of capacitance C having a charge Q under a potential $V$ is

Question 349 : The amount of work done is increasing the voltage across the plates of a capacitor from $5V$ to $10V$ is $W$. The work done in increasing it from $10V$ to $15V$ will be :

Question 350 : The potential energy of system of two equal negative point charges of $2\mu C$ each held 1 m apart in air is ($k = 9 \times 10^9\, SI \,unit$)

Question 351 : The capacitance of a variable capacitor joined with the battery of $100$V is changed from $2\mu F$ to $10\mu F$. What is the change in the energy stored in it?

Question 352 : The capacity of a condenser is $4 \times 10^{-6}$ farad and its potential is 100 volts. The energy released on discharging it fully will be

Question 353 : The energy stored in a capacitor of capacitance $C$ having a charge $Q$ under a potential $V$ is

Question 354 : A capacitor of capacity C$_{1}$ charged up to V volt and then connected to an uncharged capacitor C$_{2}$.Then final P.D. across each will be:

Question 355 : $R=100\ k\Omega$ and $C=1\ \mu F$ are connected in a series with a $12\ volt$ battery. What is the maximum energy stored in the capacitor:

Question 356 : A metallic sphere of radius $18cm$ has been given a charge of $5\times { 10 }^{ -6 }C$. The energy of the charged conductor is :

Question 357 : A 16 pF capacitor is connected to 70 V supply. The amount of electric energy stored in the capacitor is:

Question 358 : If a capacitor having capacitance of $1200\mu F$ is charged at a uniform rate of $100\mu C/s$, what is the time required to increase its potential by $20$ volts?

Question 359 : A parallel plate capacitor of $1\mu F$ capacity is discharging through a resister. If its energy reduces to half in one second. The value of resistance will be?

Question 360 : The energy stored in a sphere of $10$ cm radius when the sphere is charged to a potential difference of $300$ V is

Question 361 : A hollow metallic sphere of radius $10\ cm$ is given a charge of $3.2\times 10^{-9}C$. The electric intensity at a point $4\ cm$ from the centre is

Question 362 : A capacitors is charged to store an energy $U$. The charging battery is disconnected. An identical capacitor is now connected to the first capacitor in parallel. The energy in each of the capacitors is

Question 363 : Three condenser of capacitance $C(\mu F)$ are connected in parallel to which a condenser of capacitance $C$ is connected in series. Effective capacitance is $3.75$, then capacity of each condenser is

Question 364 : A highly conducting sheet of aluminium foil of negligible thickness is placed between the plates of a parallel plate capacitor. The foil is parallel to the plates at distance $\dfrac{d}{2}$ from positive plate where $d$ is distance between plates. If the capacitance before the insertion of foil was $10 \; \mu F$ , its value after the insertion of foil will be:

Question 365 : A potential difference of $5\ V$ is applied across a conductor of length $10\ cm$. If drift velocity of electrons is $2.5\times\ 10^{-4}\ m/s$, then electron mobility will be

Question 366 : The force between two point charge in vacuum is $15\ N$. If a brass plate is introduced between them will -

Question 367 : In a $AC$ circuit the potential difference across an inductance and resistance joining in series are respectively $16\ V$ and $20\ V$. The total potential difference across the circuit is:

Question 368 : A parallel plate capacitor consists of two circular plates each of 
radius $12cm$ and separated by $5.0mm$. The capacitor is being 
charged by an external source. The charging current is constant and is 
equal to $0.15A$. The rate of change of potential difference between the plates will be :

Question 370 : Energy stored in between the plates of parallel plate capacitor of area $A$, separated by distance $d$ is:

Question 371 : Three point charges $3nC, 6nC$ and $9nC$ are placed at the corners of an equilateral triangle of side $0.1\ m$. The potential energy of the system is :

Question 372 : If E is the electric field intensity of an electrostatic field, then the electrostatic energy density is proportional to:

Question 373 : An uncharged aluminium block has a cavity within it. The block is placed in a region where a uniform electric field is directed upward. Which of the conditions in the interior of the block's cavity?

Question 374 : n identical capacitors are connected in parallel to a potential difference V. These capacitors are then reconnected in series, their charges being left undisturbed. The potential difference obtained is :

Question 375 : Charges $1\mu c$ are placed at each of the four corners of a square of side $2\sqrt { 2 } m$. The potential at the point of intersection of the diagonals is _________ $\left( K=9\times { 10 }^{ 9 }SI\quad unit \right) $

Question 376 : A parallel plate capacitor consists of two circular plates each of 
radius $12cm$ and separated by $5.0mm$. The capacitor is being 
charged by an external source. The charging current is constant and is 
equal to $0.15A$. The rate of change of potential difference between the plates will be :

Question 377 : Two equal charges of magnitude Q each are placed at a distance d apart. Their electrostatic energy is E. A third charge $-Q/2$ is brought midway betway these two charges. The electrostatic energy of the system is now.

Question 378 : The force between two point charge in vacuum is $15\ N$. If a brass plate is introduced between them will -

Question 379 : Water is not used as a dielectric between the plates of a capacitor because its.

Question 380 : Two charges of $4 \mu C$ each are placed at the corners of A and B of an equilateral triangle ABC of side length $0.2m$ in air. The electric potential at C is :$\left ( \dfrac{1}{4\pi \epsilon _{0}}=9\times 10^{9} \right )$

Question 381 : Three capacitors each of capacity $4 \mu F$ are to be connected in such a way that effective capacitance is $6 \mu F$. This can be done by

Question 382 : An uncharged parallel plate capacitor filled with a dielectric of dielectric constant K is connected to an air filled identical parallel capacitor charged to potential $V_1$. If the common potential is $V_2$, the value of K is

Question 383 : Write T against true and F against false in the statements. Lightening conductor cannot protect a building from lightening.

Question 384 : A bullet of mass $2 g$. is having a charge of $2\:\mu C$. Through what potential difference must it be accelerated, starting from rest, to acquire a speed of $10\:m/s$?

Question 385 : Assertion: The dielectric constant is a number without dimensions. Reason: Dielectric constant is a ratio.

Question 386 : Intensity of an electric field (E) depends on distance $r$. In case of dipole, it is related as :

Question 387 : In a regular polygon of n sides, each corner is at a distance r from the centre. Identical charges are placed at (n-1) corners. At the centre, the magnitude of intensity is E and the potential is V.The ratio V/E is

Question 388 : A charge $-2\ \mu C$ at the origin, $-1\ \mu C$ at $+7\ cm$ and $1\ \mu C$ at $-7\ cm$ are placed on the X-axis. The mutual potential energy of the system is:

Question 389 : The electric field at a distance 2 cm from the centre of a hollow spherical conducting shell of radius 4 cmhaving a charge of $2 \times 10^{-3}$ C on its surface is :

Question 390 : The ratio of the resultant capacities when threecapacitors of $2 \mu F , 4 \mu F$ and $6 \mu F$ areconnected first in series and then in parallel is

Question 391 : A $5\mu F$ capacitor is charged to 12 V. The positive plate of the capacitor is connected to the negative terminal of a 12 V battery and vice versa. Find the heat developed in the connecting wires :

Question 393 : We increase the charge on the plate of a capacitor, it means

Question 394 : The plates of capacitor are charged to a potential difference of $100\ V$and are then connected across a resistor. The potential difference across the capacitors decays exponentially with time. After $1$second the potential difference between the plates of the capacitor is $80\ V$. The fraction of the stored energy which has been dissipated is :

Question 395 : From a supply of identical capacitors rated $8\;\mu F, 250 \;V$ the minimum number of capacitors required to form a composite of $16\;\mu F, 1000 \;V$ is

Question 396 : Consider the two idealised systems (i) a parallel plate capacitor with large plates and small separation and (ii) a long solenoid of length $L >> R$, radius of cross - section. In (i) $\bar{E}$ is ideally treated as a constant between plates and zero outside. In (ii) magnetic field is constant inside the solenoid and zero outside. These idealised assumptions, however, contradict fundamental laws as below.

Question 397 : Two equal positive charges are kept at points A and B. The electric potential at the points between A and B (excluding these points) is studied while moving from A to B. The potential

Question 398 : Capacity of a parallel plate condenser is $10 \mu F$ when the distance between the plates is 8 cm. If the distance between the plates is reduced to 4 cm, its capacity will be :

Question 399 : Electric field in a region is given as $\vec E = 2 \hat i$. A charge of $1 C$ is placed at $x=1m$ and a charge of $2 C$ is placed at $x=2m$. Find the total energy of the system of charges. (Assume potential at $x=0$ is zero)

Question 400 : The separation between the plates of a parallel-plate capacitor is made double while it remains connected to a cell :

Question 401 : An air capacitor C connected to a battery of e.m.f. V acquires a charge q and energy E. The capacitor is disconnected from the battery and a dielectric slab is placed between the plates. Which of the following statements is correct?

Question 402 : Three charges $2q, -q,$ and $-q$ are located at the verticesof an equilateral triangle. At the center of the triangle,

Question 403 : Out of the given statements which of the following are true : A) Work done in moving a charge on equipotential surface is zero.B) Electric lines of force are always normal to equipotential surface.C) When two like charges are brought closer, the electrostatic potential energy of the system is decreased.D) Electric lines of force converge at positive charge and diverge at negative charge.

Question 404 : Three charges $-q, Q, -q$ are placed at equal distance on a straight line. If the total potential energy of the system is zero, then $ Q:q $ is:

Question 405 : A charged particle having a charge of $-2\times 10^{-6}C$ is placed close to a non conducting plate having a surface charge density as $4\times 10^{-6} Cm^{-2}$. What will be the force of attraction between them :

Question 406 : A parallel plate condenser has a uniform electric field E (V/m) in the space between the plates. If the distance between the plates is d(m) and area of each plate is $A(m^2)$ the energy (joules) stored in the condenser is :

Question 407 : Two point charges $2q$ and $8q$ are placed at a distance $r$ apart. Where should a third charge $-q$ be placed between them, so that the electrical potential energy of the system is minimum?

Question 408 : Three point charge -q, +q and -q are placed along straight line at equal distances (say r meter). Electric potential energy of this system of charges will be if +q charge is in the middle.

Question 409 : A system consists of two charges 4 $\mu C$and -3 $\mu C$with no external field placed at (-5 cm, 0, 0) and (5 cm, 0, 0) respectively. The amount of work required to separate the two charges infinitely away from each other is

Question 410 : A parallel plate condenser has plates of area $200\mathrm { cm } ^ { 2 }$ and separation $0.05\mathrm { cm } .$ The space between plates have been filled with a dielectric having $\mathrm { k } = 8$ and then charged to $300$ volts. The stored energy:

Question 411 : An electric charge $10^{-3}\mu C$ is placed at the origin (0, 0) of X-Y co-ordinate system. Two points A and B are situated at $(\sqrt 2, \sqrt 2)$ and (2, 0) respectively. The potential difference between the points A and B will be :

Question 412 : The capacity of a parallel plate condenser without any dielectric is C. If the distance between the plates is doubled and the space between the plates is filled with a substance of dielectric constant $3$, the capacity of the condenser becomes:

Question 413 : A$\displaystyle 40\mu F$capacitor in a defibrillator is charged to $3000 V$.The energy stored in the capacitor is setthrough the patient during a pulse of duration $2ms$, The power delivered to the patient is :

Question 414 : The capacity of a parallel plate condenser is $C$ . Its capacity when the separation between the plates is halved will be :

Question 415 : A parallel plate capacitor has a capacity $80\times 10^{-6}\ F$ when air is present between the plates. The volume between the plates is then completely filled with a dielectric slab of dielectric constant $20$. The capacitor is now connected to a battery of $30\ V$ by wires. The dielectric slab is then removed. Then, the charge that passes now through the wire is :

Question 416 : The energy of a parallel plate capacitor when connected to a battery is $E$. With the battery still in connection, if the plates of the capacitor are separated so that the distance between them is twice the original distance, then electrostatic energy becomes :

Question 417 : A parallel plate capacitor has area of each plate A, the separation between the plates is d. It is charged to a potential V and then disconnected from the battery. The amount of work done in filling the capacitor completely with a dielectric constant k is :

Question 418 : A parallel plate capacitor is charged and then disconnected from the charging battery. If the plates are now moved farther apart by pulling at them by means of insulating handles, then:

Question 419 : Two similar parallel plate capacitors each of capacity $C_o$ are connected in series, The combination is connected with a voltage source of $V_o$. Now separation between the plates of one capacitor is increased by a distance $d$ and the separation between the plates of another capacitor is decreased by the distance $d/2$ The distance between the plates of each capacitor was $d$ before the change in separation. Then, select the correct choice :

Question 420 : A parallel plate capacitor of plate separation $2\ mm$ is connected in an electric circuit having source voltage $400\ V$. If the plate area is $ 60 cm^3 $ then the value of displacement current for time period of $ 10^{-6} sec $ will be

SATYAM

Teacher

Class Details:- Class 12 | Physics | classroom is a positive place where a student can come to work toward specific goals set before them in the class objectives. The teacher is to be positive, organized, outgoing, confident, and compassionate.

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