Question 4.15: Find the voltage at which the reverse current in a germanium...

We know that the current of a PN junction diode is

I=I_{0}\left(e^{\frac{V }{V_{T} } }-1 \right)

Therefore,           -0.90=I_{0}\left(e^{\frac{V }{V_{T} } }-1 \right)

where                   V_{T}=\frac{T}{11.600}=26  mV

-0.9=\left(e^{\frac{V}{0.026} }-1 \right)

0.1=e^{\frac{V}{0.026}}

Therefore,            V = – 0.06 V