Question

In an \( npn \) transistor circuit, the collector current is \( 10 \) mA. If \( 95\% \) of the electrons emitted reach the collector, then the base current is nearly:

• A. \( 5.3 \) mA
• B. \( 53 \) mA
• C. \( 35 \) mA
• D. \( 0.53 \) mA

Hint:

For an \( npn \) transistor, \( I_E = I_B + I_C \), and \( \eta \) is the percentage of electrons reaching the collector.

Answer 1

The Correct Option is D

Step 1: Use Transistor Current Relation For an \( npn \) transistor: \[ I_E = I_B + I_C \] The efficiency \( \eta \) is given by: \[ \eta = \frac{I_C}{I_E} \] Step 2: Compute Base Current Given \( \eta = 95\% \): \[ I_E = \frac{I_C}{0.95} = \frac{10}{0.95} = 10.53 \text{ mA} \] \[ I_B = I_E - I_C = 10.53 - 10 \] \[ I_B = 0.53 \text{ mA} \] Thus, the correct answer is \( 0.53 \) mA.