# Homework Help: Question on linear system

1. Nov 12, 2007

1. The problem statement, all variables and given/known data

Hi ,
I would like to have some help with the question wheter or not a half wave rectifier ( one diode) is a linear cicuit. I would also like to know if the system is time invariant.

The context is fourier series. In a earlier question ,we wer asked to find the fourier series of the half wave rectifier.

2. Relevant equations

3. The attempt at a solution

I think that it is non linear since a diode is a nonlinear device.
About time invariant, I have some problem on it.

Thank you
B

2. Nov 12, 2007

### wildman

You are correct as far as linear goes. Linear means straight line and a quick look at a diode voltage vs current graph will confirm that is anything but a straight line.

As far as time invariant goes, answer the question: I have an input A that gives output B at time X. At time X+y (where y is any number), I have the exact same input A, does it always have the same output B? or no? If it always has the same output then it is time invariant, otherwise no.

Last edited: Nov 12, 2007