In an extrinsic n-type semiconductor, the free electrons donated by the impurity atoms occupy energy levels in

For a transistor, current gain $(\beta)=50$. To change the collector current by $350 \mu \mathrm{~A}$, the base current should be changed by

When n-p-n junction transistor is used as an amplifier in common emitter mode,

Assuming that junction diode is ideal, the current in arrangement shown in figure