Question

Two cells of emf \(E_1\) and \(E_2\) with internal resistances \(r_1\) and \(r_2\) respectively, are connected in parallel by connecting their positive terminals together and negative terminals together. Deduce an expression for equivalent emf and equivalent internal resistance of the combination.

Hint:

For two cells connected in parallel, \[ E_{\text{eq}} = \frac{E_1r_2+E_2r_1} {r_1+r_2} \] and \[ r_{\text{eq}} = \frac{r_1r_2}{r_1+r_2}. \] If both cells have equal internal resistances, the equivalent emf becomes the arithmetic mean of the two emfs.

Answer 1