Question

An accumulator is being charged from a 12.5 V source (Fig.). The internal resistance of the accumulator is 1Ω. What is the electromotive force of this accumulator if the charging current is 0.5 A.

Answer 1

Answer: ε = 12V.

Explanation:

If a branch of a circuit contains a source whose electromotive force is ε, the current in this branch is determined by this e.m.f. and the difference of potential applied to the ends of the branch. The accumulator being charged is connected as shown in Fig. The current flows in the direction opposed to the e.m.f. ε. Ohm's law for this part of the circuit may be written V — ε = IR. Therefore ε = IR— V.