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NCERT Class XII Chapter
Semiconductor Electronics
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Question : 9 of 19
Marks: +1, -0
For a CE-transistor amplifier, the audio signal voltage across the collector resistance of 2 kΩ is 2 V. Suppose the current amplification factor of the transistor is 100, find the input signal voltage and base current, if the base resistance is 1 kΩ
Solution:  
Here RC = 2 kΩ = 2000 Ω,
RBR_B = 1 kΩ = 1000 Ω, β = 100, V0V_0 = 2 V
(i) Voltage gain, V0Vi\frac{V_0}{V_i} = βRCRB\frac{\beta R_C}{R_B} or 2Vi\frac{2}{V_i} = 100 × 20001000\frac{2000}{1000}
∴ Input signal voltage, ViV_i = 0.01 V.
(ii) IBI_B = ViRB\frac{V_i}{R_B} = 0.01 V1000 Ω\frac{0.01\,\mathrm{V}}{1000\,\Omega} = 0.01 V1×103 Ω\frac{0.01\,\mathrm{V}}{1\times 10^3\,\Omega} = 1 × 10−510^{-5} A = 10 µ A
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