Question

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

(a) 24 V

(b) 48 V

(c) 12 V

(d) 4 V

The question was posed to me in an interview for job.

The origin of the question is Advanced Problems on Superposition Theorem in section Useful Theorems in Circuit Analysis of Network Theory

Answer 1

Correct option is (a) 24 V

Best explanation: Using Superposition Theorem, we get,

V∆ = −0.4V∆ × 10 + 5 × 10

Solving for V∆, we get, V∆ = \(\frac{5 × 10}{1+0.4×10}\) = 10 V

Again by using Superposition Theorem, we get, I∆ = \(\frac{10}{5+20} – 0.4V_∆  \frac{20}{5+20}\)

Or, I∆ = \(\frac{10}{25} – 0.4V_∆  \frac{20}{25} = -\frac{70}{25}\) A

Thus, VO is given by, VO = 10 − 5I∆

∴ VO = 24 V.