Question

In a CB mode of a transistor the current through the emitter is 6 mA. If the current gain of the transistor is 0.95 then its base current is

transistor

• A. 0.2 mA
• B. 0.3 mA
• C. 0.5 mA
• D. 0.4 mA
• E. 0.8 mA

Answer 1

The Correct Option is D

In a Common Base (CB) mode of a transistor, the relationship between the emitter current (\( I_E \)), base current (\( I_B \)), and collector current (\( I_C \)) is given by the following equations:

\[ I_E = I_B + I_C \]

The current gain (\( \beta \)) of the transistor is related to the collector current \( I_C \) and the base current \( I_B \) by the equation: \[ I_C = \beta \cdot I_B \] We are given that the current gain \( \beta = 0.95 \) and the emitter current \( I_E = 6 \, \text{mA} \). Since \( I_E = I_B + I_C \), we can substitute \( I_C = \beta \cdot I_B \) into this equation: \[ I_E = I_B + \beta \cdot I_B = I_B (1 + \beta) \] Substituting the given values: \[ 6 \, \text{mA} = I_B (1 + 0.95) \] \[ 6 \, \text{mA} = I_B \times 1.95 \] Solving for \( I_B \): \[ I_B = \frac{6 \, \text{mA}}{1.95} = 3.08 \, \text{mA} \] Therefore, the base current \( I_B \) is approximately 0.4 mA.

Correct Answer:

Correct Answer: (D) 0.4 mA