Physics - Semiconductors Question with Solution | TestHub

Voltage gain $A_V$ is the ratio of output voltage to input voltage.

$A_V=\frac{V_{out}}{V_{in}}=\frac{I_{out}{R}_L}{I_{in}{r}_i}$

Since the a.c. current gain is $\beta =\frac{I_{out}}{I_{in}}$,

$A_V=\beta \left(\frac{R_L}{r_i}\right)$

Power gain $A_P$ is the ratio of output power to input power.

$A_P=\frac{P_{out}}{P_{in}}=\frac{I_{out}^2{R}_L}{I_{in}^2{r}_i}$

$A_P={\left(\frac{I_{out}}{I_{in}}\right)}^2\left(\frac{R_L}{r_i}\right)={\beta }^2\left(\frac{R_L}{r_i}\right)$

Answer: $\beta \left(\frac{R_L}{r_i}\right),{\beta }^2\left(\frac{R_L}{r_i}\right)$