The correct relation between α (ratio of collector current to emitter current) and β (ratio of collector current to base current) of a transistor is:

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

Correct answer: α = β/(1+β)

Solution

With alpha = Ic/Ie and beta = Ic/Ib, and Ie = Ib + Ic, we get alpha = beta/(1+beta). Equivalently beta = alpha/(1-alpha).

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