Important questions class 12 physics electric potential and capacitance
Electrostatic Potential and Capacitance
1. The figure shows the field lines of a positive charge. Is the work done by the field in moving a small positive charge from Q to P positive or negative?
2. For any charge configuration, equipotential surface through a point charge is normal to the electric field. Justify.
3. Two charges and are placed at points A and B, 5 cm apart. Depict an equipotential surface of the system.
4. Why electrostatic potential is constant throughout the volume of the conductor and has the same value as on its surface?
5. Why the potential inside a hollow spherical charged conductor is constant and has the same value as on its surface?
6. Why there is no work done in moving a charge from one point to another on an equipotential surface?
7. A hollow metal sphere of radius 5 cm is charged such that potential on its surface is 10 V. What is the potential at the centre of the sphere?
8. Can two equipotential surfaces intersect each other? Justify your answer.
9. Draw the equipotential surface due to a single point charge.
10. Name the physical quantity whose SI unit is J/C. Is it a scalar or a vector?
11. A capacitor has been charged by a DC source. What are the magnitude of conduction and displacement current when it is fully charged?
12. Distinguish between a dielectric and a conductor.
13. Define the term dielectric constant of a medium. What is its unit?
14. A metal plate is introduced between the plates of a charged parallel plate capacitor. What is its effect on the capacitance of the capacitor?
15. Define dielectric strength of a dielectric.
16. What is a capacitor? On what factors, the capacitance of a parallel plate capacitor depends?
17. Define polar and non-polar materials. Give examples for each.
18. Define the term capacitance of a capacitor. What is its unit?
19. What is energy density? Write an expression for the energy density of a parallel plate capacitor.
20. The following graph shows the variation of charge Q with voltage V for two capacitors K and L. In which capacitor is more electrostatic energy stored?