Question

The value of ZTh in the circuit shown below is?

(a) Z3+(Z1Z2/(Z1+Z2))

(b) Z1+(Z3Z2/(Z3+Z2))

(c) Z2+(Z1Z3/(Z1+Z3))

(d) (Z1Z2/(Z1+Z2))

I had been asked this question in an international level competition.

This interesting question is from Thevenin’s Theorem topic in section Steady State AC Analysis of Network Theory

Answer 1

Correct option is (a) Z3+(Z1Z2/(Z1+Z2))

To explain I would say: The thevenin’s equivalent form of any complex impedance consists of an equivalent voltage source and an equivalent impedance. The thevenin’s impedance is ZTh = Z3+(Z1Z2/(Z1+Z2)).