In the transistor circuit shown,assume that the voltage drop between the base and the emitter is $0.5\ V$. What will be the ratio of the voltage across resistances $R_2$ and $R_1$ in order to make this circuit function as a source of constant current,$I = 1\ mA$?

For transistor action:
$(1)$ Base,emitter and collector regions should have similar size and doping concentrations.
$(2)$ The base region must be very thin and lightly doped.
$(3)$ The emitter-base junction is forward biased and base-collector junction is reverse biased.
$(4)$ Both the emitter-base junction as well as the base-collector junction are forward biased.
Which one of the following pairs of statements is correct?

In an $N-P-N$ transistor amplifier,the collector current is $9 \ mA$. If $90\%$ of the electrons emitted from the emitter reach the collector,then:

In a transistor, if $\frac{I_C}{I_E} = \alpha$ and $\frac{I_C}{I_B} = \beta$. If $\alpha$ varies between $\frac{20}{21}$ and $\frac{100}{101}$, then the value of $\beta$ lies between:

An $N-P-N$ transistor conducts when:

For a common base configuration of a $PNP$ transistor,$\frac{I_C}{I_E} = 0.96$. Then,the maximum current gain in common emitter configuration will be: