A battery of emf `epsilon` volt internal resistance `r` ohm is joined in series with two resistances `X` and `Y` ohm in a closed circuit. A standard cell of emf `1.06 V` and a galvanometer are joined in series and the combination is connected across `X`. The galvanometer shows no deflection when `X = 60 Omega and Y = 224 Omega` or when `X = 40 Omega and Y = 140 Omega` Calculate the values of `E and r`

Answer

`28 Omega`

Explanation

(i) `(epsilon)/((60 + 224+ r)) xx 60 = 1.06`
(ii) `(epsilon)/((40 + 140+ r)) xx 40 = 1.06`
On solving we get `epsilon = 5.51 V and r = 28 Omega`