Question

In the circuit given below, the value of I is __________

(a) 2.47 A

(b) 5.67 A

(c) 8.43 A

(d) 1.43 A

This question was posed to me in an interview for internship.

The origin of the question is Advanced Problems on Reciprocity Theorem topic in chapter Useful Theorems in Circuit Analysis of Network Theory

Answer 1

Correct option is (d) 1.43 A

To explain I would say: Equivalent Resistance, REQ = [[((30 || 20) + 20) || 20] + 20]

= \(\Big[\Big[\left(\left(\frac{30 × 20}{30+20}\right) + 20\right) || 20\Big] + 20\Big]\)

= [[(12 + 20) || 20] + 20]

= [[32 || 20] + 20]

= \(\Big[\left(\frac{32 × 20}{32+20}\right) + 20\Big]\)

= [12.31 + 20] = 32.31 Ω

The current drawn by the circuit = \(\frac{200}{32.31}\) = 6.19 A

Now, by using current division rule, we get, I2Ω = 1.43 A.