Question

In a transistor $\beta =$ 50 , the change in the voltage across 5k $\Omega$ resistor which is connected in collector circuit is 5V. The change is base current is

• A. 10$\mu$ A
• B. 20$\mu$ A
• C. 50$\mu$ A
• D. 100$\mu$ A

Answer 1

Answer: (B)

20$\mu$ A

Given:
$\beta =50$
$R_L=5K\Omega =5\times {10}^3$
$V_C=5V$

The collector current is:
$I_C=\frac{V_C}{R_L}$
$I_C=\frac{5}{5\times {10}^3}$
$I_C={10}^{-3}A$

The current gain for transistor is:
$\beta =\frac{I_C}{I_B}$
$I_B=\frac{I_C}{\beta }$
$I_B=\frac{{10}^{-3}}{50}$
$I_B=0.02\times {10}^{-3}A$
$I_B=20\times {10}^{-6}A=20\mu A$