Question

Five cells each of emf e and internal resistance r are connected in series. If due to oversight one cell is connected wrongly then equivalent emf and internal resistance of the combination are

Answer 1

Emf of the 5 identical cells of emf E are connected in series. Then the net emf of the combination should be 5E. But, one of them is wrongly connected i.e. with its polarity reversed. This cell will cancel the emf of another cell. Thus, equivalent number of cells in the combination = E + E + E + E - E = 3E. Net emf of the combination = 3E. However, internal resistance of all the cells connected in series will add up irrespective of the fact that two of the cells are wrongly connected. Net internal resistance of the combination = 5r. Ans 3E, 5r

Answer 2

Answer:8E, 10r

Explanation:

Equivalent emf =9E-E(i.e. Wrongly connected)

=8E

Equivalent resistance = 10r