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MHT CET Medical202624 April 2026Morning ShiftPhysicsSemiconductorsActual

For a common emitter amplifier, the audio signal voltage across the collector resistance of 2 k is 4 V. If the current amplification factor of the transistor is 100 and the base resistance is 1 k , then the input voltage is

Options

  1. A10 mV
  2. B15 mV
  3. C20 mV
  4. D25 mV

Correct answer

C. 20 mV

Step-by-step solution

Output voltage V_o = 4 V Collector resistance R_c = 2 k = 2000 Collector current I_c = V_o R_c = 4 2000 = 2 10⁻³ A Current amplification factor = 100 Base current I_b = I_c = 2 10⁻³ 100 = 2 10⁻⁵ A Base resistance R_b = 1 k = 1000 Input voltage V_i = I_b R_b = (2 10⁻⁵) 1000 = 2 10⁻² V = 20 mV Answer: 20 mV

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