Two copper spheres of radii r1 and r2 having charges q1 and q2 are connected by means of a wire. What is the electric condition that no charge flows between them?
(a) q1/r1 = q2/r2
(b) q1/r1 > q2/r2
(c) q1/r1 < q2/r2
(d) q1/r1 = -q2/r2