Question

For the circuit shown, the resistance R is variable from 2Ω to 50Ω. What value of RS results in maximum power transfer across terminals ‘ab’.

(a) 1

(b) 2

(c) 3

(d) 4

This question was posed to me during an internship interview.

Question is from Maximum Power Transfer Theorem in portion Useful Theorems in Circuit Analysis of Network Theory

Answer 1

The correct option is (b) 2

The best explanation: As RL is fixed, the maximum power transfer theorem does not apply. Maximum current flows in the circuit when RS is minimum. So RS = 2Ω.