Semiconductor Electronics Materials Devices and Simple Circuits - Result Question 69
71. A common emitter amplifier has a voltage gain of 50, an input impedance of $100 \Omega$ and an output impedance of $200 \Omega$. The power gain of the amplifier is
(a) 500
(b) 1000
(c) 1250
(d) 50
[2010, 2007]
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Answer:
Correct Answer: 71. (c)
Solution:
- (c) Power gain $=$ voltage gain $\times$ current gain
$=V_G \cdot I_G=\frac{V_0}{V_i} \cdot \frac{I_0}{I_i}$
$=\frac{V_0^{2}}{V_i^{2}} \cdot \frac{R_i}{R_0}=50 \times 50 \times \frac{100}{200}$
$=\frac{2500}{2}=1250$
