Chapter 9, Problem 6RAT

A bimetallic strip used in thermostats relies on the fact that different metals have different

(a) specific heat capacities.

(b) thermal energies at different temperatures.

(c) rates of thermal expansion.

(d) All of these.

To determine

The correct option for the statement "A bimetallic strip used in thermostats relies on the fact that different metals have different".

Answer to Problem 6RAT

The correct option for the statement "A bimetallic strip used in thermostats relies on the fact that different metals have different" is option (c).

Explanation of Solution

The molecules of a hot substance have more average translational kinetic energy that results in molecules moves farther away due to the fast jiggling. Most of the substance gets contracted when they cooled down and expands when heated. The expansion of substance differs for different substances. Sometimes it is noticeable, and sometimes the expansion is too small to be noticed.

In case of bimetallic strip, it is made up of two different types of materials, one is brass and another is iron, so the thermal expansion for both the material will be different. When it is heated, the brass expands more as compare to iron, so it bends towards the brass, and it bends towards the iron when it cools down. This behavior of strip is used to maintain the circuit. So, a bimetallic strip used in thermostats relies on the fact that different metals have different thermal expansion rates.

Conclusion:

Therefore, the correct option for the statement "A bimetallic strip used in thermostats relies on the fact that different metals have different" is option (c).