Trevelyan rocker

Ball and ring; Plate with hole

Relevant Resource questions :

Concepts demonstrated :

• thermal expansion of solids

• bimetal strip
• bunsen burner and matches
• retort stand
• CCD camera

• Place bimetal strip on the retort stand and heat.

None.

Physics involved

Two different metals stuck together will expand at different rates when heated. These different expansion rates will cause the combined strip to bend.

How to use the Demonstration :

• Revise the expansion of different materials and discuss joining two metals together.
• Ask students aboout the expected result when heated (POE). Perhaps a class vote. Will it stay the same or move?
• Perform the demonstration and discuss.
• Discuss the use of bimetal strips in various applications.

• Bimetal strip in circuit breaker.
• Fire alarm.
• Hot water system.
• Automatic turn off for electric hot water jug.

• Remake the experiment with different bimetal strips or geometries.
• Would be good to add animations that can go in Powerpoint which show how a bimetal strip is used in a fire alarm or circuit breaker.
• Make a poster for Open Days.