In an $n$-type semiconductor, electrons are majority charge carriers and holes are minority charge carriers. The charge of an $n$-type semiconductor is

The region in the output voltage versus input voltage graph where a transistor can be used as an amplifier is

The voltage gain of a transistor in common emitter configuration is 160 . The resistances in base and collector sides of the circuit are $1 \mathrm{k} \Omega$ and $4 \mathrm{k} \Omega$ respectively. If the change in base current is $100 \mu \mathrm{~A}$, then the change in output current is