For a common emitter configuration, if α and β have their usual meanings, the incorrect relationship between α and β is:

1/α = 1/β + 1
α = β/(1−β)
α = β/(1+β)
α = β²/(1+β²)

Correct answer: α = β/(1−β)

Solution

Correct CE relations: alpha=beta/(1+beta) and equivalently 1/alpha=1/beta+1. The relation alpha=beta/(1-beta) is the incorrect one, so it is the required answer (index 1).

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