Thermostat is a device which is used to maintain a desired temperature in a system like refrigerator, air-conditioner,iron and in a number of devices.
Thermostat works on the principle of thermal expansion of solid materials.
A bimetallic thermostat device consists of a strip of two different metals having different coefficients of linear expansion.
The bimetallic strip works as an electric contact breaker in an electric heating circuit. The circuit is
broken when the desired temperature is reached.
Due to difference in the coefficients of linear expansion of two metals, The bimetallic strip bends in the
form of a downward curve and the circuit is broken. The metallic strip is in contact with a screw 'S'.
When it becomes hot, bends downward and contact at 'P' is broken. Thus the current stops flowing
through the heating coil. When the temperature falls, the strip contracts and the contact at 'P' is
Bimetallic thermostats are widely used in numerous appliances such as refrigerator, airconditioner, Iron, ice plants etc.
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