The part of a transistor which is heavily doped to produce a large number of majority carriers is

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

In a common emitter transistor amplifier,the output voltage and input voltage have a phase difference of

An $NPN$ transistor is used in common emitter configuration as an amplifier with $1\,k\Omega$ load resistance. $A$ signal voltage of $10\,mV$ is applied across the base-emitter. This produces a $3\,mA$ change in the collector current and $15\,\mu A$ change in the base current of the amplifier. The input resistance and voltage gain are:

In a junction transistor,the collector current changes by $6.8 \,mA$,if the emitter current is changed by $7 \,mA$. For such a transistor,the current amplification factor is

In an $n-p-n$ transistor circuit,the collector current is $10 \, mA$. If $90 \%$ of the electrons reach the collector,then the emitter current will be: