Question

The current gain $\alpha$ of a transistor is defined as

• A. the ratio of change in collector current to the change in emitter current for a constant value of collector voltage in a common base arrangement.
• B. the ratio of change in collector current to the change in base current for a constant collector voltage in a common collector arrangement.
• C. the ratio of change in collector current to the change in base current for constant collector voltage in a common emitter arrangement.
• D. the ratio of change in emitter current to the change in collector current for a constant emitter voltage in a common emitter arrangement

Answer 1

The correct option is A the ratio of change in collector current to the change in emitter current for a constant value of collector voltage in a common base arrangement.

By definition, current gain $\alpha$ in transistor is defined as the ratio of change in collector current to the change in emitter current for a value of collector voltage in a common base arrangement.

Mathematically: $\alpha =\frac{I_C}{I_E}$ (at $V_{CC}=constant$)