* Thermal Expansion: When metals are heated, they expand. Different metals expand at different rates.

* Bimetal Strip: A bimetal strip is made of two different metals bonded together.

* Unequal Expansion: When the bimetal strip is heated, the metal with the higher coefficient of thermal expansion expands more than the other metal.

* Bending: This uneven expansion causes the strip to bend towards the side with the lower coefficient of thermal expansion, as it has expanded less.

Example:

* Brass: Has a higher coefficient of thermal expansion than steel.

* Brass-Steel Bimetal Strip: When heated, the brass side will expand more, causing the strip to bend towards the steel side.

This property of bimetal strips makes them useful in various applications like thermostats, fire alarms, and some types of electrical switches.