The saturation current of a P-N junction germanium at 27°C is $10^{−5}$ amp. The potential required to be applied in order to obtain a current of 250mA in forward bias will be:

0.57 V 0.48 V 0.26 V 0.63 V

0.26 V

$I_f=I_s[e^{qV/KT}-1]$ or $e^{\frac{qV}{KT}}=\frac{I_f}{I_s}+1=\frac{250×10^{-3}}{10^{-5}}+1=25001$ or $\frac{qV}{KT}=10.126$ $∴V=\frac{10.126×1.38×10^{-23}×300}{1.6×10^{-23}}=0.26V$