Ball and Ring

PIRA 4A30.21

Brief Description

Most solids, like gases, expand when heated and contract when cooled. This demonstration takes advantage of this fact with a metal ball and ring. At room temperature the diameter of the ball is almost as large as the inner diameter of the ring, allowing the ball to go through it. However, if the ball is heated over fire or the ring is cooled in liquid nitrogen, the ball will no longer fit.

Materials

Metal Ball and Ring Sets, Propane Torch, Liquid Nitrogen.

2 rods one with a ring on the end and another with a ball both made of steel.

Notes and Safety

There are several different sets made of different metals and metal alloys. You can mix and match them to show that different materials have different coefficients of thermal expansion.

The ball and ring sets for this demo are located in the far back drawer labelled "4A Thermometer".

Please be careful when handling the liquid nitrogen and hot metal.