In which of the configurations of a transistor, the power gain is highest?

In a common emitter amplifier,a change of $0.2 \text{ mA}$ in the base current causes a change of $5 \text{ mA}$ in the collector current. If the input resistance is $2 \text{ k}\Omega$ and the voltage gain is $75$,what is the load resistance used in the circuit?

The dc common emitter current gain of an $n-p-n$ transistor is $50$. The potential difference applied across the collector and emitter of a transistor used in $CE$ configuration is $V_{CE} = 2 \ V$. If the collector resistance $R_{C} = 4 \ k\Omega$,the base current $(I_{B})$ and the collector current $(I_{C})$ are:

For a transistor,$\alpha_{dc}$ and $\beta_{dc}$ are the current ratios. Then the value of $\frac{\beta_{dc}-\alpha_{dc}}{\alpha_{dc} \cdot \beta_{dc}}$ is

In a common emitter transistor amplifier circuit,the input resistance is $1.8 \text{ k}\Omega$ and the output is obtained across a load resistance of $9 \text{ k}\Omega$. The alternating current gain is $70$. Corresponding to an a.c. input voltage of $6 \text{ mV}$,the output voltage will be: (in $\text{ V}$)

An oscillator is nothing but an amplifier with