Question

the \\( \beta \mathrm{dc} \\) of a transistor is its

select one:

o a. power gain

o b. internal resistance

o c. voltage gain

o d. current gain

Explanation:

In transistor terminology, \( \beta_{\text{DC}} \) (also known as \( h_{FE} \)) represents the direct - current current gain of a transistor. It is defined as the ratio of the collector current (\( I_C \)) to the base current (\( I_B \)) in a common - emitter configuration, i.e., \( \beta_{\text{DC}}=\frac{I_C}{I_B} \).

• Option a: Power gain of a transistor is related to both voltage and current gain (\( P_{\text{gain}} = A_V\times A_I \)), and \( \beta_{\text{DC}} \) is not a direct measure of power gain.
• Option b: Internal resistance of a transistor is a different parameter, related to the impedance characteristics of the transistor's terminals, and has nothing to do with \( \beta_{\text{DC}} \).
• Option c: Voltage gain of a transistor in a common - emitter configuration is \( A_V=-\beta_{\text{DC}}\frac{R_C}{r_e'} \) (where \( R_C \) is the collector resistor and \( r_e' \) is the emitter resistance), so \( \beta_{\text{DC}} \) is not the voltage gain itself.
• Option d: Since \( \beta_{\text{DC}}=\frac{I_C}{I_B} \), it is the current gain of the transistor.

Answer:

d. current gain