A common emitter amplifier has a voltage gain of 50, an input impedance of 100 Ω and an output impedance of 200 Ω. The power gain of the amplifier is

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Correct answer: (C) 1250. AC power gain = ( output power)/(Change in input power) = (∆V_c×∆i_c)/(∆V_i×∆i_b)=(∆V_c)/(∆V_i)×(∆i_c)/(∆i_b)=A_V×β_AC where A_V is voltage gain and β_AC is AC current gain. Also, A_V=β_AC×resistance gain =R_o/R_i Given, A_V=50, R_o=200 Ω, R_i=100 Ω Hence, 50 = β_AC×200/100 ∴ β_AC=25 Now, AC power gain = A_V×β_AC = 50 × 25 = 1250

A common emitter amplifier has a voltage gain of $50$ , an input impedance of $100 Ω$ and an output impedance of $200 Ω .$ The power gain of the amplifier is

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