Question

Find the current through 3Ω resistor in the circuit shown below.

(a) 1

(b) 2

(c) 3

(d) 4

This question was addressed to me in an interview for job.

Enquiry is from Reciprocity Theorem topic in section Useful Theorems in Circuit Analysis of Network Theory

Answer 1

Right choice is (b) 2

The explanation is: The 6Ω resistor is parallel to 3Ω resistor and the resultant is in series with 2Ω resistor. Total current from source = 12/(2+(6│|3))=3A. Current through 3Ω resistor = 3 × 6/(6+3)=2A.