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JEE Main 2021 (18 Mar, Shift 1) · Junction Transistor

Junction Transistor question from JEE Main 2021 (18 Mar, Shift 1)

Q72JEE Main 2021 · 18 MAR · SHIFT 1Medium

Junction Transistor

An npn transistor operates as a common emitter amplifier with a power gain of 106. The input circuit resistance is 100Ω\Omega and the output load resistance is 10 KΩ\Omega. The common emitter current gain 'β\beta' will be ________. (Round off to the Nearest Integer).

Numerical answer type. Work it out, then open the answer.

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Answer: 100

  1. Power gain of CE amplifier: Ap=β2RoRiA_p = \beta^2 \dfrac{R_o}{R_i}
  2. 106=β2×104100=100 β210^6 = \beta^2 \times \dfrac{10^4}{100} = 100\,\beta^2
  3. β2=104⇒β=100\beta^2 = 10^4 \Rightarrow \beta = 100
  4. So β=100\beta = 100.
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