The input signal given to a $C.E.$ amplifier having a voltage gain of $126$ is $V_i = 2 \cos \left(12 t + \frac{\pi}{3}\right)$. The corresponding output signal will be

When $n-p-n$ transistor is used as an amplifier :

In a $PNP$ transistor,the base is the $N$-region. Its width relative to the $P$-region is

To use a transistor as an amplifier,which of the following conditions must be satisfied?

Which two of the following statements are true for a transistor?
$(1)$ The base,emitter,and collector regions of a transistor have the same size and doping concentration.
$(2)$ The base region is thin and lightly doped.
$(3)$ The emitter-base junction is forward-biased,and the base-collector junction is reverse-biased.
$(4)$ Both the emitter-base junction and the base-collector junction are forward-biased.

In a silicon transistor,a change of $7.89 \, mA$ in the emitter current produces a change of $7.8 \, mA$ in the collector current. What change in the base current is necessary to produce an equivalent change in the collector current (in $mA$)?