In a common emitter transistor amplifier, AC current gain is $65$, the load resistance is $5400\,\Omega$ and input resistance of the transistor is $450\,\Omega$. The voltage gain is

In the band structure of n-type semiconductor , the free electrons donated by impurity atoms occupy energy levels in

The Boolean expression for the given combination of logic gates is

In a transistor, comparing the doping of emitter, base and collector, the part which is heavily doped and that which is lightly doped are respectively