# In a common base amplifier circuit , calculate the change in base current if that in emitter current is 2 mA and α = 0.98

Q: In a common base amplifier circuit , calculate the change in base current if that in emitter current is 2 mA and α = 0.98

(a) 0.04 mA

(b) 1.96 mA

(c) 2 mA

(d) 98 mA

Ans: (a)

Sol: $\large \alpha = \frac{I_c}{I_e}$

Since Ie = Ib + Ic

$\large \alpha = \frac{I_e – I_b}{I_e}$

$\large 0.98 = \frac{2 – I_b}{2}$

Ib = 0.04 mA