Question

A bimetallic strip consists of brass and iron when it is heated it bends into an arc with brass on the convex and iron on the concave side of the arc. This happens because

• A. brass has a higher specific heat capacity than iron
• B. density of brass is more than that of iron
• C. it is easier to bend an iron strip than a brass strip of the same size
• D. brass has a higher coefficient of linear expansion than iron

Answer 1

Answer: (D)

brass has a higher coefficient of linear expansion than iron

Answer 2

Two strips of equal lengths but of different materials (different coefficient of linear expansion) when joined together, is called bimetallic strip, and can be used in thermostat to break or make electrical contact. This strip has the characterstic property of bending on heating due to unequal linear expansion of the two metals.
The strip will bend with metal of greater $\alpha$ on outer side $i e$, convex side.