In potentiometer a balance point is obtained, when
(a) The e.m.f. of the battery becomes equal to the e.m.f. of the experimental cell
(b) The p.d. of the wire between the +ve end to jockey becomes equal to the e.m.f of the experimental cell
(c) The p.d. of the wire between +ve point and jockey becomes equal to the e.m.f. of the battery
(d) The p.d. across the potentiometer wire becomes equal to the e.m.f. of the battery
