What is the basic constitutional unit in the electronic circuit?

For a transistor,$\frac{1}{\alpha_{DC}} - \frac{1}{\beta_{DC}}$ is equal to [where $\alpha_{DC}$ and $\beta_{DC}$ are current amplification factors].

In the following common emitter circuit,$\beta=100$ and $V_{CE}=7 \text{ V}$. If $V_{BE}$ is negligible,then the base current is (in $\text{ mA}$)

$A$ common emitter amplifier has a voltage gain of $50$, an input resistance of $100 \ \Omega$, and an output resistance of $200 \ \Omega$. What is the power gain of the amplifier?

In an $n-p-n$ transistor amplifier,the collector current is $8 \ mA$. If $80 \%$ of the electrons from the emitter reach the collector,then ($\alpha$ and $\beta$ are current ratios):

In an $n-p-n$ transistor,$10^{10}$ electrons enter the emitter in $10^{-6} \ s$. If $2\%$ of the electrons are lost in the base,the current amplification factor $\beta$ is: