The classic demonstration of volume thermal expansion - great for drawing and keeping the attention of your student(s).
* Put the ball through the ring;
* Heat the ball until it is very hot;
* Try to bring the ball back through the ring. The ball cannot pass back through the ring until it has cooled!
Once you have their attention, try some other variations:
* Heat the ring instead of the ball. Does the ball go through the ring now?
* Heat the ring and the ball. Can it go through now?
Historically, the ball and ring experimental apparatus has been referred to as 'sGravesande Apparatus. Willem Jakob van 'sGravesande (1688-1742) wrote one of the first Newtonian physics textbooks in 1720-1721.
The original 'sGravesande ring is currently at the Universidade de Coimbra museum in Portugal. Look at a photograph of the 'sGravesande ring.
Materials: brass ring and ball, wooden handles.
Dimensions: 10-11" (25.4-28.0 cm) long, 1" (2.5 cm) ball diameter.