# Poles and zeros

Discussion in 'Homework Help' started by MilK, Apr 7, 2010.

1. ### MilK Thread Starter Member

Mar 1, 2008
25
0
Hi,

For RLC / RC / RL circuit, with soure and load R, Can i determine the number of zeros just by inspection? as in by looking at the circuit, without finding the transfer function. I just need to know how many zeros there are, not the exact value.

I know i can find how many poles by looking at the number of Cap & Inductors, but zeros?

Thx in adv

2. ### Ghar Active Member

Mar 8, 2010
655
72
Zeroes are much trickier to spot and depend on your input / output definition while the poles are the same for any transfer function in that circuit.

I don't think there's any simple way to do it except by learning to recognize certain situations that give you a zero.

3. ### MilK Thread Starter Member

Mar 1, 2008
25
0
what kind of situation?

4. ### Ghar Active Member

Mar 8, 2010
655
72
The most basic one is that a series RC with the output defined across the resistor gives you a zero at f = 0