The phase difference between the input voltage and the output voltage in a common emitter amplifier is (in $^{\circ}$)

In a transistor,the base is made very thin and is lightly doped with an impurity because:

An oscillator is nothing but an amplifier with

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

$A$ $npn$ transistor is connected in common emitter configuration in a given amplifier. $A$ load resistance of $800 \,\,\Omega$ is connected in the collector circuit and the voltage drop across it is $0.8 \,\, V$. If the current amplification factor is $0.96$ and the input resistance of the circuit is $192 \,\,\Omega$,the voltage gain and the power gain of the amplifier will respectively be

$A$ transistor having a $\beta$ equal to $80$ has a change in base current of $250 \mu A$. What is the change in collector current?