I just learned about electrets from wikipedia. Electrets are permanant electric dipoles, essentially the electrical analogue of magnets. My questions, then:

 

1) Why have I never heard of electrets before? Not in college, not in high school, and my physics prof wanted a journal reference before she would believe they exist.

 

2) Do electrets make good toys? If I'm not mistaken, small electrets would allow me to see an electric field, right?

erm... most of Todays Microphones are Electret, I`m almost Shocked that you (or your prof) have never heard of them!????

I think it may be an engineering term. I don't recall hearing it in physics classes, though certainly the concept of an electric dipole was covered.

Oh, I have heard of electric dipoles before, but not any that were macroscopic and permanent. Just things like water molecules and such. The wiki article gives a recipe using waxes, and I never heard of such things. I'll make one if it makes a good toy

Well, I've never heard of them either. Although, I've always wondered what might happen if you froze water while it was under influence of a strong electric field ^^

 

Anyone here have any hands-on experience with these electrets? Will they for instance bend water streaming from a faucet like an electrified comb does?

They are called electrets by analogy with magnets. I'm suprised the prof hadn't heard of them but to be fair, except in microphones, they are pretty obscure.

Actually, a magnet would techincally be one, since a magnetic field creates an electric one... and so on and so force.

 

You could vibrate a magnet quick enough to cause electric to run through a wire on the other side of the room for instance

since a magnetic field creates an electric one

 

ehh that would be a changing magnetic field creates an electric one. static fields don't do squat.

That is why I mentioned vibrating the magnet

yeah, but that you make an alternating field electrets have a static field

my Alpha radiation detector is electret based also, so it must be reasonably common I expect.

 

Commoner than I thought. I have a similar detector (in need of general maintainance I think) and I didn't know it was electret based. Do you know how it works?

as far as I know (I`m by Far NOT an expert) the Alpha passes through the aluminised mylar, knocks off electrons underneath in the cavity and that`s then picked up by some sort of detector.

I know the cct employs a HT line also, it`s function I have no idea, perhaps it`s a way to accelerate the particles to give them more clout when they hit the detector???

So they're fairly common then. But do they make good toys?