Question

The value of the voltage VO in the circuit given below is __________

(a) 20 V

(b) 30 V

(c) 40 V

(d) 50 V

I got this question during an online interview.

I'd like to ask this question from Advanced Problems on Superposition Theorem topic in portion Useful Theorems in Circuit Analysis of Network Theory

Answer 1

Correct answer is (b) 30 V

For explanation: Using Superposition Theorem, the current IB is given by,

IB = \(\frac{70}{4||20+2||10} × \frac{20}{4+20} + \frac{50}{10+4||20||2} × \frac{20||2}{4+20||2} – \frac{2I_B}{20||2+4||10} × \frac{10}{4+10}\)

Or, IB = \(\frac{35}{3} + \frac{25}{18} – \frac{11}{36}\) IB

Now, Solving for IB, we get, IB = \(\frac{\frac{35}{3}+\frac{25}{18}}{1+\frac{11}{36}}\) = 10 A

Now, VO = 70 − 4ib

∴ VO = 30 V.