Question

For a common-emitter transistor amplifier, the current gain is 60 .60. If the emitter current is 6.6 ma then its base current is

Answer 1

The base current is $0.15 mA.$

Explanation:

Given, a common emmiter configuration:

Current gain(β) = 60 and emitter current ($I_{E}$) = 6.6 mA

To find, base current = ?

We know that,

$\alpha = \frac{\beta}{1+\beta}$

⇒ $\alpha = \frac{60}{1+60}=\dfrac{60}{61}$

∵ $\alpha=\frac{I_{C}}{I_{E}}$

⇒ Collector currenr, ${I_{C}=\alpha \times {I_{E}$

⇒ ${I_{C}=\dfrac{60}{61} \times 6.6 mA$

= 6.45 mA$</strong></p><p><strong>∴ Base current, [tex]I_{B} =I_{E} -I_{C} =6.6-6.45 mA= 0.15 mA$

Hence, the base current is $0.15 mA$.