Question

A function N (S) is said to have a pole (or zero) at infinity if the function N (1/S) has a pole (or zero) at S = ?

(a) ∞

(b) 2

(c) 0

(d) 1

This question was addressed to me by my college director while I was bunking the class.

The question is from Properties of Driving Point Functions in chapter S-Domain Analysis of Network Theory

Answer 1

The correct option is (c) 0

To elaborate: A function N (S) is said to have a pole (or zero) at infinity, if the function N (1/S) has a pole (or zero) at S = infinity. A zero or pole is said to be of multiplicity ‘r’ if (S-Z)^r or (S-P)^r is a factor of P(s) or Q(s).