why are the densities different between a new and old set of pennies different? i know that it has something to do with the percentage of copper change after 1984... but how much was that change?!
Because copper was becoming too expensive, some time ago they started using Zinc and simply electroplating a Copper layer on it. I'm not sure when they started this nor how much. There was a television show which demonstrated this a while ago. They used acid to dissolve away the Zinc core, and only a very thin shell of copper remained. You might be able to google the words penny composition to get the specific details on the internet Hope this helps.
