4A30.10-Bimetalic Strip

Video: Watch this demo

Instructor’s video

Description: This demonstration shows the thermal properties (thermal expansion) of two different metals.

Equipment:

• Bimetallic Strip
• Bunsen burner
• Matches
• LN2 and container

Setup Procedure:

1. Connect the bun sen burner to the gas valve in the classroom.

Demonstration Procedure:

1. Light the Bunsen burner.
2. Show students that the two strips are flat.
3. Stick the bimetallic strip into the fire for several seconds until it bends.
4. Show the students that the strip is bent. Since both sides of the bimetallic strip are color coded, tell the students what side it bent to.
5. Place the bimetallic strip into some LN2 and wait a for it to cool down and bend.
6. Show students that it is now bent the other way (towards the other color strip).
7. This happens because one metal expands and contracts faster than the other.
8. When finished, turn off the gas valve.

Open Flame
Keep away from flammable materials.

Liquid Nitrogen
Use caution when working with liquid nitrogen, as it is very cold.
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