Question

Find the current in the circuit.

(a) 0.54A

(b) 0.65A

(c) 0.67A

(d) 0.87A

I had been asked this question by my college professor while I was bunking the class.

This interesting question is from Delta Star Transformation topic in section Network Theorems of Basic Electrical Engineering

Answer 1

Right answer is (a) 0.54A

The explanation: The 3 5 ohm resistors are connected in delta. Changing it to star:

R1=R2=R3 = 1.67 ohm.

One of the 1.67 ohm resistors are connected in series with the 2 ohm resistor and another 1.67 ohm resistor is connected in series to the 3 ohm resistor.

The resulting network has a 1.67 ohm resistor connected in series with the parallel connection of the 3.67 and 4.67 resistors.

The equivalent resistance is 3.725A.

I=2/3.725 = 0.54A.