Calculate the emf and internal resistance of the equivalent cell to replace the below combination of cells
Four identical cells of emf E and internal resistance r are to be connected in series. Suppose if one of the cells is connected wrongly, the equivalent emf and effective internal resistance of the combination is:
Obtain the equivalent emf and internal resistance of a parallel combination of 2 cell of emf E1 and E2 and internal resistance R1 and R2.