ivandh,
Your analogy is correct. There has been a change in the metals used to create American cents...and this has occurred during the minting process within a particular year. So, for instance, a 1982 Lincoln cent can be found with two different compositions.
Here is a breakdown of the Lincoln Cent, Memorial Reverse, for those who may have an interest.
1959 - 1962: weight 3.11 grams, composition .950 copper, .050 tin & zinc
1962 - 1982: weight 3.11 grams, composition .950 copper, .050 zinc
1982 - present: weight 2.5 grams, core composition .992 zinc, .008 copper, with a plating of pure copper...total content .975 zinc, .025 copper










Due to the increasing value of copper worldwide some low-denomination UK coins are almost approaching a scrap-metal value that is greater than their face currency value.
Better to take your surplus coins to a metal-dealer rather than the bank.
We already have that problem, pennies cost more to make than their face value, even though they're mostly zinc.
Cents prior to 1981 (or is it 83?) contain more copper, analogous to old coins that used to have actual silver in them.