A common emitter amplifier has a voltage gain of 50. An input impedance of $100\mathrm{\Omega }$ and an output impedance of $200\mathrm{\Omega }.$ The power gain of the amplifier is

$\text{ Voltage gain }=50$

$\text{ Input resistance, }{R}_i=100\Omega$

$\text{Output resistance, }{R}_o=200\Omega$

$\text{ Resistance gain }=\frac{R_o}{R_i}=\frac{200\Omega }{100\Omega }=2$

$\text{ Power gain }=\frac{(\text{ Voltage gain }{)}^2}{\text{ Resistance gain }}=\frac{50\times 50}{2}=1250$