Question
What is the beta of a bipolar junction transistor?
Answer Options
- A) The frequency at which the current gain is reduced to 0.707
- B) The change in collector current with respect to the change in base current
- C) The breakdown voltage of the base-to-collector junction
- D) The switching speed
Correct Answer: B
Explanation
The term beta (\beta), often represented as h_{FE} (DC gain) or h_{fe} (AC gain), is the fundamental measure of current gain in a common-emitter configuration of a bipolar junction transistor (BJT). This characteristic determines how much the input current is amplified to control the output current.
Beta is defined as the ratio of the output collector current (I_C) to the input base current (I_B). More precisely for small-signal (AC) analysis, the beta is the ratio of the change in collector current (\Delta I_C) with respect to the change in base current (\Delta I_B). [cite_start]Thus, beta is the change in collector current with respect to the change in base current, representing the transistor’s current amplification factor.
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