Question

In the figures given below, Value of RA, RB and RC are 20 Ω, 10 Ω and 10 Ω respectively. The resistances R1, R2 and R3 in Ω are ________

(a) 2.5, 5 and 5

(b) 5, 2.5 and 5

(c) 5, 5 and 2.5

(d) 2.5, 5 and 2.5

The question was asked during a job interview.

The origin of the question is Advanced Problems on Network Theory topic in portion Network Theory and Complex Circuit Diagram of Network Theory

Answer 1

The correct answer is (a) 2.5, 5 and 5

Easiest explanation: R1 = \(\frac{R_B R_C}{R_A+R_B+R_C} = \frac{100}{40}\) = 2.5 Ω

R2 = \(\frac{R_A R_C}{R_A+R_B+R_C} = \frac{200}{40}\) = 5 Ω

R3 = \(\frac{R_B R_A}{R_A+R_B+R_C} = \frac{200}{40}\) = 5 Ω.