An $NPN$ transistor circuit is arranged as shown in the figure. It is:

In a $CE$ circuit,the collector of a transistor is kept at a constant voltage $V_C = 1.5 \ V$. When the base current changes from $100 \ \mu A$ to $150 \ \mu A$,the collector current changes from $5 \ mA$ to $10 \ mA$. The current gain $\beta$ for this transistor is:

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.

What is the phase difference between the input and output voltage for a common-base amplifier?

In an $n-p-n$ transistor amplifier,the collector current is $9 \ mA$. If $90 \%$ of the electrons emitted reach the collector,then

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