Which among the following is the temperature regulating component of an automatic electric iron?

A thermostat is an important component of an electric iron that regulates its temperature. The main function of the thermostat in an electric iron is to make sure that the iron doesn’t get too hot if it is left unattended to for a period of time.

When an electric current is passed through a coil in an electric iron, the coil becomes very hot. Through conduction, the heat is transferred to the flat base plate of the electric iron which is used to iron our clothes.

However, the heating element continues to get hotter so far there is a continuous drawing of electricity from the power supply. This result into a lot of energy wastage and may damage the cloths.

At this point, thermostat comes in because it is important that the iron doesn’t heat up to a temperature that is hazardous.

The thermostat in iron makes use of a bimetallic strip. This bimetallic strip is made up of two different types of metals (brass and iron) with a different coefficient of expansion bonded together.

Therefore, in the presence of heat, the bimetallic strip expands differently. The metallic strip is connected to a contact spring through small pins.

The bimetallic strip remains in physical contact with a contact point at a moderate temperature. However, at a temperature of the iron above a certain limit, the strip tends to bend towards the metal with a lower coefficient of expansion. At this point, the strip stops to be physically connected to the contact point and current stops flowing because of an opening of the circuit.

Position (a) is when the iron is at normal temperature

Position (b) is when the iron becomes too hot