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ECE · Q53

Electronic Devices And Circuits

Engineering and GATE · ECE · question 53

Q53

The forward amplification factor of a transistor corresponds to

A.
the power gain of CE amplifier
B.
the current gain of CB amplifier
Answer
C.
the voltage gain of CC amplifier
D.
the voltage gain of CE amplifier

Answer: Option B

Solution

Answer: Option B
Solution:
In transistor configurations, different parameters are used to describe amplification properties.

Forward amplification factor is denoted by α (alpha) and it represents the current gain in Common Base (CB) configuration.

It is defined as the ratio of collector current to emitter current:

α = Ic / Ie

The value of α is always less than 1 but very close to it (typically between 0.95 and 0.99).

Option A: Incorrect, because power gain of CE amplifier depends on both current and voltage gain, not on forward amplification factor.

Option C: Incorrect, because CC amplifier has a voltage gain nearly equal to 1, which is not related to forward amplification factor.

Option D: Incorrect, because voltage gain of CE amplifier is different and not defined by α.

Thus, the forward amplification factor of a transistor corresponds to the current gain of CB amplifier.