# Prepare for Physics oral test too during lockdown

## ELECTROSTATICS (Module 2)

1. Define electric field.
2. Define electric field strength (intensity of electric field).
3. What is an electric dipole?
4. Define electric dipole moment.
5. Is the electric dipole moment a scalar or a vector quantity?
6. What is the direction of electric dipole moment?
7. What is the unit of electric dipole moment?
8. What are electric field lines?
9. State the characteristics of electric field lines.
10. Why two electric field lines never intersect each other?
11. Comment on the statement, “The electric field lines (electric lines of force) are imaginary, but what they represent is a reality”
12. Electric lines of force always enter or emerge normal to the surface of a conductor, justify.
13. What is the ratio of electric field strengths on axial position to equatorial position if both the points are at the same distance from the centre of the dipole?
14. What is the angle between the electric field at a point on the axial position and the electric field at a point on the equatorial position?
15. Write the expression for torque on a dipole in a uniform electric field.
16. Which are the positions of minimum torque and maximum torque of an electric dipole in a uniform electric field?
17. Write the expression for work done in rotating a dipole in a uniform electric field.
18. Write the expression for potential energy of a dipole in a uniform electric field with its axis making an angle θ with the electric field.
19. Define electric flux.
20. State Gauss’ law
21. Compare the variation of electric field strength with distance in the case of (a) a point charge (b) a dipole (c) a uniformly charged long straight wire and (d) a uniformly charged infinite plane sheet of charge.
22. What is a Gaussian surface?
23. State the principle of superposition of electric fields
24. Which are the positions of (a) stable equilibrium and (b) unstable equilibrium of a dipole in a uniform electric field?
25. Which are the positions of maximum potential energy and minimum potential energy of an electric dipole in a uniform electric field?

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