Bipolar transistors

What is the approximate common-emitter current gain β of a bipolar transistor whose common-base current gain α is 0.99?

  1. A0.99
  2. B9.9
  3. C99
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Answer: C. 99

α and β are related by β = α / (1 − α). For α = 0.99, β = 0.99 / 0.01 = 99. A small change in α toward 1 changes β greatly.

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  1. Which correctly describes the Early effect in a bipolar transistor?
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