Four identical cells of emf E and and internal resistance r are to be connected in series . Suppose if one of the cell is connected wrongly , the equivalent emf and effective internal resistance of the combination is

Options

A. 2E and 2r
B. 2E and 4r
C. 4E and 2r
D. 4E and 4r

Answer

B

Explanation

If all are connected correctly, `E_("eff")= 4E`
`r_("eff")= 4r`
Now `E_("eff") = 2E rArr r_("eff")= 4r`