are caps and coils linear circuit elements?

...... Phil

The idealized models of capacitors and inductors show them as being linear, because they obey superposition.

Real world capacitors and inductors can show nonlinear behavior if you push them hard enough -- particularly electrolytic caps and iron-core inductors, but anything will spark over if you make the voltage high enough, or overheat if you make the current high enough.

A linear system is one that obeys superposition; for a system h that takes signal x to generate signal y, y = h(x). If you can show that

h(x1 + x2) = h(x1) + h(x2)

for _any_ two signals x1 and x2 then the system obeys superposition* and it is linear.

• Saying h(a1*x1 + a2*x2) = a1*h(x1) + a2*h(x2) is sufficient, but not necessary -- with enough analysis you can show that this relationship flows from the prior definition of superposition that I showed.

An element is linear if applying N times the input (say, voltage) always results in exactly N times some output (like current maybe). We consider ideal resistors, capacitors, and inductors to be linear.

A circuit is linear if applying N times an input produces N times the output. Note that N could be any number, positive or negative. So if N=-1, that implies that if you invert the input, the output exactly inverts in response.

Unlike resistors, the IV curves of Ls and Cs involve time... the curves are sort of three dimensional. But that doesn't make them nonlinear.

John

Which implies that Ls and Cs are linear in time, too.

John

Charters and description lines.

sci.electronics.basics Elementary questions about electronics.

"A forum for discussion of electronics where there is no such thing as a stupid question. Beginners questions. Discussion of electronics education. Requests for other sources of information."

Mark Zenier snipped-for-privacy@eskimo.com Googleproofaddress(account:mzenier provider:eskimo domain:com)

The Basics group is where Phil has to go to find people he thinks he's smarter than, so he can abuse them for being dumb.

Is that smart?

John

Most of us learn to ignore Phil early on.

Cheers! Rich

You know, Ill Phallusin'. >;->

"John Larkin = dribbling autistic DOLT "

...... Phil

You might be onto something there Phil!

Yeah, that's the closest-to-rational thing he's said in months.

John

You remind me of a guy I knew in the military. He appeared totally worthless. He spent 6 months going to dental appointments every day so he could get off early to work on his boat. In the meantime others had to do his work. That wasn't actually so bad because when he did his own work we usually ended up redoing it. Then one day someone actually told him he served no purpose. He thought for a minute and the said "everyone needs a bad example too". You seem very similar. I've never seen anyone as unpleasant for no reason. You stand as a frequent reminder to not hit send if you don't have anything constructive to say. Finally, I have to admit that as far as bad examples go, you're the tops!

I fully realize that nothing I could say or do would fix you. I'm not that powerful. My intention here was to write this on the record for myself as a permanent reminder to watch what I write and how I treat people. I have been accused of being challenged in the area of "tact" so I need reminders and you do a fine job.

For electronic content, I think the idea John brought up about three dimensional representations is strange and deserves a little more thought.