An n – p – n transistor circ

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Target Exam

CUET

Subject

Physics

Chapter

Semiconductors and Electronic Devices

Question:

An n – p – n transistor circuit has $α$ = 0.985.

If $I_c = 2mA$, then value of $I_b$ is -

Options:

0.03 mA

0.003 mA

0.66 mA

0.015 mA

Correct Answer:

0.03 mA

Explanation:

$α=\frac{I_c}{I_e}=\frac{I_c}{I_c+I_b}=0.985$

$I_c = 0.985 (I_c + I_b)$

$I_c = 0.985\, I_c + 0.985\, I_b$

$0.985 I_b = 0.015 I_c = 0.015 × 2 mA$

$I_b = \frac{0.015 ×2}{0.985}= 0.03 mA$

$I_b≈0.03mA$