Two identical thin rings

PHYSICS · Single correct · A Level · Physics · Fields and their consequences · Fields and their consequences

Problem

Two identical thin rings, each of radius

R

, are coaxially placed a distance

R

apart. If

q_1

and

q_2

are respectively the uniformly distributed charges on the two rings, the work done in moving a charge

q

from the centre of one ring to the centre of the other is (a) zero (b)

\frac{q(q_1-q_2)(\sqrt{2}-1)}{\sqrt{2}(4\pi\varepsilon_0R)}

(c)

\frac{q\sqrt{2}(q_1+q_2)}{4\pi\varepsilon_0R}

(d)

q\left(\frac{q_1}{q_2}\right)(\sqrt{2}+1)\sqrt{2}(4\pi\varepsilon_0R)