Compound Bars

The bimetallic strip is a tried and true demonstration of thermal expansion. It's available from all sorts of sellers (Flinn, Arbor Sci, bunches of other places). Invariably, though, the bimetallic strip (also known as a compound bar) is exactly the same from every seller. Yeah, the handle changes, but the metal strip is exactly the same - brassy on one side, silvery on the other, curving toward the brassy side.

This summer, though, I went searching to see if there were other bimetallic strips available, other combinations of metals to demonstrate.

It turns out that there are...sort of...

The four bars above are available from Arbor Scientific, but they come with a bit of a warning.

Of the three customer reviews on the Arbor Scientific page, one is pretty solidly and simply negative, "These pieces are just poorly made, and do not work at all. They are riveted together and tend to buckle instead of bend."

Yup, you can see clearly that those four compound bars are riveted together not smoothly joined as the more common bimetallic strip is. Clearly there's some reason why the cheap and omnipresent bimetallic strip is so omnipresent. It works. The two metals are - assumedly - easily and permanently joined.

Has anybody bought or used the four-bar set? If so, what are your experiences?

If anybody wants to see a couple of nice videos explaining the compound bar, check these...