An electric dipole is placed at an angle of ? = 30 with an electric field intensity 2 X 105 N /C . It experiences a torque equal to 4 N m.The charge on the dipole, if the dipole length is 2 cm, is

1 point

(1) 8mC

(2) 2m C

(3) 5m C

(4) 7 ?C

Other:

2. Two metallic spheres of radius 2 cm and 4 cm and both carry equal charges of 30 ?C. If two spheres are connected by conducting wire, then amount of charges will be transferred from one to other is

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(1)20 ?C

(2)40 ?C

(3)10 ?C

(4) 30 ?C

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3. Force between two identical spheres charged with same charge is F. If 50% charge of one sphere is transferred to second sphere then new force will be

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(1) ? F

(2) 3/8F

(3) 3/ 2 F

(4) F

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4. The point charges 3 ?C and 4? C are placed at a separation of 7 m. The medium between them is of two types as shown in figure , the electric force acting between them is

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(1) 1.75 10-3 N

(2) 1.73 10-4 N

(3) 0.18 10-4 N

(4) 0.18 103 N

Other:

5. The force between two charges placed in air at a distance r apart is F. Then the force betweenthe same two charges if a dielectric having k = 4 and thickness r/2 is introduced between charges is

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1) 4/9 F

2) 9/4 F

3) 9/16 F

4 ) 16/9 F

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6. Net electric flux emerging out for the Gaussian surface S is

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ZERO

3SQUARE 2q/E0

q/E0

-q/E0

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7. An infinite line charge is at the axis of a cylinder of length 1 m and radius 7 cm. If electric field at any point on the curved surface of cylinder is 250 NC?1, then net electric flux through the cylinder is ( Nm2C-1 )

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1) 1.1 X 10 2

2) 9.74 X 10-6

3) 5.5 X 106

4) 2.5 x 102

Other:

8. Two wires of linear charge density ? passing through a sphere of radius R and a cube of sides R so that the flux linked with them is maximum. Then the ratio of flux of sphere to the cube is .......

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SQUARE ROOT OF 2

1/SQUARE ROOT OF 2

2/SQUARE ROOT OF 2

SQUARE ROOT OF 3/2

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9. There are n electrons of charge e in a drop of oil of density ? . It is in equilibrium in an electric field E. Then the radius of drop is

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A

B

C

D

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10. The radius of gold nucleus (Z = 79) is 7 X 10-15 m. If the volume charge density on nucleus is and electric field on the surface of nucleus is E then electric field at the centre of nucleus radius is......

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(1) E

(2) 2 E

(3) E/3

(4) E/2

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11. The electric field at a point on equatorial line of a dipole and direction of the dipole moment

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(1) Will be parallel

(2) Will be in opposite direction

(3) Will be perpendicular

(4) Are not related

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12. Which of the following is not true about electric charge?

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(1) Charge on a body is always integral multiple of certain charge known as charge of electron

(2) Charge is a scalar quantity

(3) Net charge on an isolated system is always conserved

(4) Charge can be converted into energy and energy can be converted into charge

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13. A point charge q1 exerts an electric force on a second point charge q2 If third charge q3 is brought near, the electric force of q1 exerted on q2

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(1) Decreases

(2) Increases

(3) Remains unchanged

(4) Increases if q3 is of same sign as q1 and decreases if q3 is of opposite sign

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14. In a uniform electric field if a charge is fired in a direction different from the line of electric fieldthen the trajectory of the charge will be a

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(1) Straight line

(2) Circle

(3) Parabola

(4) Ellipse

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15. A positively charged pendulum is oscillating in a uniform electric field pointing upwards. Its time period as compared to that when it oscillates without electric field

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(1) Is less

(2) Is more

(3) Remains unchanged

(4) Starts fluctuating

Other:

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