Electric dipole is placed near a uniformly charged large non-conducting surface.

Options

A. Net electric force on electric dipole is zero.
B. Net torque on electric dipole may be zero.
C. Net torque on electric dipole may be non-zero
D. Net electric force on electric dipole may be non-zero.

Answer

A, B, C

Explanation

We know that electric field intensity near a large conducting plate is uniform. Both the charges of dipole will always experience forces of equal magnitude and in opposite directions, hence net force becomes zero and option (a) is correct but option (d) is not correct.
If axis of the dipole is perpendicular to the plate then the lines of action of forces on positive and negative charges will coincide and that will make net torque equal to zero. Option (b) is correct.
If axis of the electric dipole is inclined with plate at an angle other than `90^@` then the lines of action of forces on the two charges will be separated from and each other and that will produce a net torque, hence option (c) is correct.