Question

Find the value of the source voltage from the following circuit.

(a) 49.2V

(b) 34.6V

(c) 65.2V

(d) 25.6V

I got this question in an interview for internship.

This interesting question is from Kirchhoff’s Laws and Network Solution in chapter Network Theorems Applied to AC Networks of Basic Electrical Engineering

Answer 1

The correct choice is (a) 49.2V

For explanation I would say: I3 =(3+j0)A

V2 =I3R=(3+j0)(8+j0)=(24+j0)V

I2=V2/Xc=(0 + j1.5) A

I1 =I2 +I3 =(0+j1.5)+(3+j0)=(3+j1.5)A

I1=(3^2+1.5^2)^1/2= 3.35A.

V1 =I1(R+jXL) =(15+j30)V

E=V1 +V2 =(39+j30)V

E=(39^2+30^2)^1/2= 49.2V.