In a transistor,the value of $\alpha$ varies between $\frac{20}{21}$ and $\frac{100}{101}$. Then the value of $\beta$ varies between

$A$ transistor is used in common emitter mode as an amplifier. Then:

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 common emitter configuration, a transistor has $\beta=50$ and input resistance $1 \text{ k}\Omega$. If the peak value of a.c. input is $0.01 \text{ V}$, then the peak value of collector current is: (in $\mu\text{A}$)

In a transistor circuit, when the base current is increased by $50 \mu A$ keeping the collector voltage fixed at $2 \ V$, the collector current increases by $1 \ mA$. The current gain of the transistor is

The phase difference between input and output voltages of a $CE$ (common emitter) amplifier circuit is........$^o$.