Two sources of current of equal emf are connected in series and have different internal resistances R1 and R2 (R2 > R1). Find the external resistance R at which the potential difference across the terminals of one of the sources (which one in particular?) becomes equal to zero?
Let, us consider the current i, flowing through the circuit, as shown in the figure. Applying loop rule for the circuit, - Δ φ = 0
So, R = R1 - R2, which is the required resistance.
