12 kilohertz

[Robert]

Per this Wikipedia article http://en.wikipedia.org/wiki/Cent_(United_States_coin) when flipping a Lincoln cent with "a good, solid strike", a pre-1982 cent will make a ringing sound somewhere in the 12 kHz range.

I bet you didn't know that. I sure didn't.

Maybe someone can confirm that?

[Bob P]

Someone had to be pretty bored, or got a nice US Government grant to figure this one out. I guess we'll all have to go out and get a meter to determine if we have 'good cents'.
Wher do you come up with this stuff Robert??

[eagames]

I had a friend that tested every 1982 cent to see if it was copper or zinc by flipping it.

If you have good ears you can hear the coppers make a zing noise as they flip. It's repeatable and zinc cents don't make the same sound.

I made the balance scale to weigh mine since I didn't want to touch or damage them by flipping them. But it's true you can use flipping noise to tell copper from zinc.

[cladking]

Sounds high to me but I never checked one.

[Rhubarb]

I will either drop the coin on a table, flip it, or use my scale when I'm at home. I'm still not that good when it comes to flipping.

Rhubarb

[Bob P]

I cut all the coins in half with a machete. If it's silver colored inside...I know I've got a zinc core cent. Pretty easy huh?????