Numerical - Anode current of SCR comprising two-transistor analogy with the gate current

What is the value of anode current of SCR comprising two-transistor analogy with the gate current of 40 mA if the gain of PNP & NPN transistors are 0.3 & 0.4 respectively?

Option:

a. 253 mA
b. 113 mA
c. 73.33 mA
d. 53.33 mA

Correct Answer: d. 53.33 mA

Explanation:

According to given data:

Gain of PNP transistor = a₁ = 0.3

Gain of NPN transistor = a₂ = 0.4

Gate current = I_G = 40 mA =0.04 A

According to the formula of anode current,


Anode current = I_A = a₂ I_G / [1-
(a₁ + a₂ )]
= ( 0.4 x 0.04 ) / [1 - ( 0.3 + 0.4)]
= 0.016 / 0.3
= 53.33 mA