Physics - Semiconductors Question with Solution | TestHub

For a transistor, the emitter current $I_E$ is the sum of the base current $I_B$ and the collector current $I_C$.

$I_E=I_B+I_C$

The current ratio $\alpha$ (common-base current gain) is defined as the ratio of collector current to emitter current.

$\alpha =\frac{I_C}{I_E}$

Since $I_C<I_E$, we have $\alpha <1$.

The current ratio $\beta$ (common-emitter current gain) is defined as the ratio of collector current to base current.

$\beta =\frac{I_C}{I_B}$

Since the base current is very small compared to the collector current ($I_C\gg I_B$), we have $\beta >1$.

Thus, $\beta >1$ and $\alpha <1$.

Answer: $\beta >1,\alpha <1$