Question

What do you mean by a bimetallic strip thermometer?

Answer 1

A bimetallic strip is a thin strip that is made up of two sub strips of two different metals. Usually these two metals expand or contract by different amounts when the temperature of the total strip increases or decreases respectively.

Complete step-by-step answer:
A bimetallic strip thermometer consists of a bimetallic strip. A bimetallic strip consists of two smaller sub strips of two different metals that usually expand or contract by different lengths when the temperature of the strip increases or contracts respectively. This happens because the two metals have different thermal coefficients of linear expansion.
The result is that as the two strips change in length by different amounts for the same temperature change in the whole strip, the total bimetallic strip bends so as to maintain the joint of the two sub strips at the two ends of the total bimetallic strip.
In a bimetallic strip thermometer, this amount of bending is measured and from this, the temperature change in the total bimetallic strip is obtained for the whole bimetallic strip.

Note: Students must note that for a bimetallic strip to work satisfactorily, both the metals should have sufficiently different coefficients of linear expression so that sufficiently different changes in length can be obtained for the same change in temperature in both metals and there is a good amount of bending freedom in the bi metallic strip. However, if the coefficients of linear expansion of one of the strips is much greater than the other, then the structure of the bimetallic strip may get distorted.