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Question:

In a common emitter transistor amplifier the audio signal voltage across the collector is 3V. The resistance of the collector is 3kΩ. If the current gain is 100 and the base resistance is 2kΩ, the voltage and power gain of the amplifier is:

200 and 1000

20 and 2000

15 and 200

150 and 15000

Solution:

The correct option is D 150 and 15000
vc=3v
Rc=3000Ω
B=100
Ic=Vc/Rc=3/3000=10⁻³A
Ib=Ic/B=10⁻³/100=10⁻⁵A
Vb=IbRb=10⁻⁵×2000=2×10⁻²V
voltage gain=Vc/Vb=3/(2×10⁻²)=150
Power gain = B × voltage gain=100×150=15000