Positive and negative point charges of equal magnitude are kept at and respectively. The work done by the electric field when another positive point charge is moved from to is [2007]

Question

Positive and negative point charges of equal magnitude are kept at $(0, 0, \frac{a}{2})$ and $(0, 0, \frac{- a}{2})$ respectively. The work done by the electric field when another positive point charge is moved from $(- a, 0, 0)$ to $(0, a, 0)$ is [2007]

Smart Achievers · Accepted Answer

(3)

Two charges make an electric dipole. A and B points lie on the equatorial plane of the dipole.

$∴$ Potential at A, $V_{A}$ = potential at B, $V_{B} = 0$

Hence, work done $W = q (V_{A} - V_{B}) = q \times 0 = 0$

Solution

Q.
Positive and negative point charges of equal magnitude are kept at $(0, 0, \frac{a}{2})$ and $(0, 0, \frac{- a}{2})$ respectively. The work done by the electric field when another positive point charge is moved from $(- a, 0, 0)$ to $(0, a, 0)$ is [2007]

1 positive

2 negative

3 zero

4 depends on the path connecting the initial and final positions

Ans.
(3)

Two charges make an electric dipole. A and B points lie on the equatorial plane of the dipole.

$∴$ Potential at A, $V_{A}$ = potential at B, $V_{B} = 0$

Hence, work done $W = q (V_{A} - V_{B}) = q \times 0 = 0$

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