Ball And Ring

Consists of a a copper plate and copper ring mounted on a lab stand, and a steel ball with a bent length of wire affixed.

Demonstrates differing thermal expansion coefficients of unlike materials; demonstrates the widening of internal holes due to thermal expansion of a volume.

• Copper ring/plate with hole on stand
• Steel ball
• Propane torch and striker

Place the ball on either the ring or the hole in the plate. Use the blow torch to apply heat evenly to the area. Due to the dissimilar coefficients of thermal expansion, the plate/ring will expand faster than the ball and the hole will widen enough for the ball to drop through. The bent length of wire attached to the ball serves to prevent the potentially-very-hot ball from getting away, it should catch on the hole after it drops through.