Thermal expansion affects bimetallic strips by causing them to bend or curve when the temperature changes. Here’s why and how it happens:
- A bimetallic strip is made of two different metals bonded together, each with a different coefficient of thermal expansion.
- When the temperature increases, both metals expand, but because their expansion rates differ, one metal tries to lengthen more than the other.
- This difference in expansion causes the strip to bend towards the metal with the lower coefficient of thermal expansion (the metal that expands less).
- Conversely, when the temperature decreases, the strip bends in the opposite direction.
- This bending effect is widely used in devices like thermostats, where the mechanical movement of the strip can open or close electrical contacts to control heating or cooling.
So, thermal expansion causes the bimetallic strip to convert temperature changes into mechanical displacement by bending due to unequal expansion of the two metals.