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# Important questions class 12 physics electric charges and fields

Updated: May 30, 2020

## [1 Mark Questions]

1. Why do the electrostatic field lines not form a closed-loop?

2. Why do the electric field lines never cross each other?

3. Why must the electrostatic field be normal to the surface at every point of a charged conductor?

4. Why must electrostatic field at the surface of a charged conductor be normal to the surface at every point? Give reason.

5. Two-point charges q1and q2are placed at a distance 'd’ apart as shown in the figure. The electric field intensity is zero at the point P on the line joining them as shown. Write two conclusions that you can draw from this. 6. Define the dipole moment of an electric dipole. Is it a scalar quantity or a vector quantity?

7. Draw a plot showing the variation of an electric field (E) with distance r due to a point charge Q.

8. A proton is placed in a uniform electric field directed along the positive X-axis. In which direction will it tend to move?

9. In which orientation, a dipole placed in a uniform electric field is in

i. stable and

ii. unstable equilibrium?

10. Two-point charges having equal charge separated by 1 m distance experience a force of 8 N. What will be the force experienced by them if they are held in the water at the same distance? (Given K water = 80).

11. A metallic sphere is placed in a uniform electric field as shown in the figure. Which path is followed by electric field lines and why? 12. Point out right or wrong for the following statement.

The mutual forces between two charges do not get affected by the presence of other charges.

13. A dipole of dipole moment p is present in a uniform electric field E. Write the value of the angle between p and E for which the torque experienced by the dipole, is minimal.

14. Consider two hollow concentric spheres, S1 and S2, enclosingcharges2Qand 4Qrespectively as shown in the figure.