Bimetallic Strip Thermostat

This demonstration uses a bonded copper–steel strip to show how temperature changes cause mechanical movement. Because the metals expand at different rates when heated, the strip bends, illustrating the principle of differential thermal expansion. This effect underpins many real-world devices, such as thermostats and circuit breakers, where heat is converted into mechanical motion for control purposes.

1. Secure the bimetallic strip on a stand.
2. Apply heat using a flame, hot plate, or lamp.
3. Observe the strip bending as one metal expands more than the other.
4. Allow it to cool and watch it return toward its original shape.

Thermal Expansion Demo: Bimetallic Strip - Physics Demos:

Homemade bimetallic strips - Thermostat demonstration - Homemade Science with Bruce Yeany:

📄 Bimetallic Strip Demonstration - Modern Teaching Aids: https://www.teaching.com.au/product/bimetallic-strip-demonstration?srsltid=AfmBOopqS09mfrGrfeSmLpF9y1yx9NtQzPghyHekJdU3EilJB9MjdihX

• Test different heat sources (flame vs. radiant lamp).
• Quantify curvature by measuring displacement after heating.
• Compare strips made of different metal combinations.
• Use cooling (ice, liquid nitrogen if available) to observe contraction.
• Link the theory to devices such as thermostats, circuit breakers, or oven temperature gauges.

• Use heat sources with care; supervise students around open flames.
• Handle the strip with tongs or heat-resistant gloves after heating.
• Ensure the strip is mounted securely before heating.
• Allow the strip to cool before touching directly.

• Why does the strip bend instead of expanding evenly?
• How does differential expansion lead to useful mechanical work?
• What everyday devices rely on bimetallic strips?
• How might engineers select materials for different applications?