Question

A circuit whose resistance is R is connected simultaneously to N similar accumulators. What is the value of the internal resistance of the accumulators if the current in the circuit is the same whether the accumulators are connected in series or in parallel?  

Answer 1

Answer: The internal resistance of each accumulator is R.

Explanation:

If ε is the e.m.f. and r the internal resistance of one accumulator, then, when connected in series, the accumulators develop a total e.m.f. of Nε, the resistance of the circuit is R + Nr, and the current is

Comparing these equations, we find that I₁ = I₂ when r = R