Poistive and negative point charges of equal magnitude are kept at `(0, 0, a/2)` and `(0, 0, (-a)/(2))` respectively. The work done by the electric field when another poistive point charge is moved from `(-a, 0, 0)` to `(0, a, 0)` is

Options

A. positive
B. negative
C. zero
D. depends on the path connecting the initial and final positions

Answer

C

Explanation

Positive and negative point charges of equal magnitude kept at `(0, 0, (a)/(2))` and `(0, 0, -(a)/(2))` form an electric dipole with centre at the origin, and axis along Z-axis. Point A(-a, 0, 0) is on X-axis and B (0, a,0) is on Y-axis at same distance from the origin as shown in the figure.

Therefore, potential at both points A and B are zero. When the charge is moved from A to B, work done by the electric field on the charge will be zero.