Question:

An npn transistor operates as a common emitter amplifier, with a power gain of 60dB. The input circuit resistance is 100Ω and the output load resistance is 10kΩ. The common emitter current gain β is:

6×10²

10²

10⁴

The correct option is D
10⁴
Av × β = Pgain
60 = 10log₁₀(P/P₀)
P = 10⁶ = β² × R₀ᵤₜ/Rᵢₙ
10⁶ = β² × 10⁴/100
β² = 10⁴
β = 100