There is a bimetallic coil in your kit. It's made of two different metal strips on top of each other, similar to the tape and foil system
you just made, and then rolled up into a spiral (which it a way
to make a very long strip be very compact).
When the temperature of the coil rises, one of the metals expands more than the other and so causes the coil to
tighten or unroll slightly.
Find a way to hold the center of the coil so that it can't turn.
For example, you could jam it onto the pointed end of a pencil, or grasp
the central end of the coil with a pair of needle-nosed pliers.
Note the position of the tab on the outside edge of the coil.
Plunge it into hot water or ice water, and notice how the outside
tab moves. It happens very quickly -- within a second. It's important
to keep the center from turning!
How large is the change? How hard do you have to push to keep the
tab in its original position?
Because the bimetallic coil makes a nice big motion and can push something,
it is frequently used to turn switches on and off in thermostats,
airconditioners, and automobile engines.
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How large is the change? How hard do you have to push to keep the
tab in its original position?