Positive 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 electirc field when another positive point charge is moved from `(-a,0,0) to (0,a,0) is `

Options

A. positive in both `I` and `III`
B. negative and appears only at the point on the sphere closest to the point charge
C. zero
D. depends on the path connecting the initial and final positions

Answer

C

Explanation

`A equiv (0a, 0, 0), B equiv (0, a, 0)`

Point charge is moved from A to b
`V_(A)=V_(B)=0 :. W=0`