Question

In the circuit given below, the current in the 20 Ω resistor is _________

(a) 5 A

(b) 1 A

(c) 1.5 A

(d) 2 A

The question was asked in homework.

Origin of the question is Advanced Problems on Reciprocity Theorem topic in portion Useful Theorems in Circuit Analysis of Network Theory

Answer 1

The correct choice is (d) 2 A

To explain I would say: Equivalent resistance, REQ = [[20 || 60] + 30]

= \(\Big[\frac{20 × 60}{20+60} + 30\Big]\)

= [15 + 30] = 45 Ω

Total current = \(\frac{120}{45}\) = 2.67 A

Current through the 20Ω resistor is, I20Ω = \(\frac{2.67 × 60}{60+20}\) = 2 A.