What happens to a bi-metal strip comprised of stainless steel and brass when heat is applied?

When heat is applied to a bi-metal strip made from stainless steel and brass, the brass expands more than the stainless steel. This difference in thermal expansion occurs because the two metals have different coefficients of thermal expansion, which is a measure of how much a material expands when heated.

Brass typically expands more than stainless steel when subjected to the same increase in temperature. As a result, when the bi-metal strip is heated, the greater expansion of brass causes the strip to bend towards the stainless steel side. This bending reaction is due to the mechanical constraints imposed by the differing expansion rates of the two metals.

Understanding the behavior of bi-metal strips is crucial in various applications, such as temperature sensing devices (like thermometers) and thermal expansion switches, where they are used to convert temperature change into mechanical movement. This principle helps to explain why the brass expands more and therefore leads to the correct interpretation of the behavior of the bi-metal strip when heated.