Bimetallic switch: Change in temperature lights cold/hot lamps.

Bimetallic switch: Change in temperature lights 'cold' or 'hot' lamps. A bimetallic strip is a two-way switch in this demo. At room temperature, the strip touches the contact that lights the blue light. When a hair dryer heats the strip, the strip bends and touches the contact that lights the red light. TEMPERATURE AND EXPANSION.