Question

A point charge of 50 uC is moved in a uniform electric field from point P to another point Q slowly. The work done by agent is 1 uJ. Potential difference Vp-Vq is
1) -20V 2) +20V
3) -10V 4) +10V

Answer 1

I think your question is ---> A point charge of 50uC is moved in a uniform electric field from point P to another point Q slowly. The work done by agent is 1 mJ. Potential difference Vp-Vq is

answer : option (2) +20 V

explanation : A point charge of 50uC is moving in uniform electric field from point P to another point Q slowly. we know, charge moves from higher potential to lower potential . so, potential at P is higher than potential at Q.

now using formula, workdone by external agent = charge × potential difference

or, $W_e=-q(V_Q-V_p)$

or, $(V_p-V_Q)=\frac{W_e}{q}$

given, $W_e$ = 1mj = 10^-3 J

and q = 50uC = 50 × 10^-6 C

then, $V_p-V_Q$ = 10^-3/(50 × 10^-6) = 20 volts

hence, option (2) is correct choice.