Question

A bimetallic strip consists of two metals: A on top and B at bottom. At temperature 00C this bimetallic strip was rigidly attached to the vertical wall with one end, so strip is horizontal. We know that coefficient of thermal expansion of metal A is less than coefficient of thermal expansion of metal B. Temperature starts to raise. What happens to the bimetallic strip?

a. nothing happens
b. it contracts in horizontal direction
c. it bends down
d. it bends up
e. it expands in horizontal direction

Answer 1

Answer:

e. it expands in horizontal direction

Explanation:

By the law of thermal expansion of metals we know that when a metal is heated it expands due to the thermal properties of its molecules.

Mathematically this expansion in its length is given by:

$\Delta l=l.\alpha.\Delta T$

where:

$l=$ original length of the metallic piece

$\alpha=$ coefficient of linear expansion

$\Delta T=$ rise in temperature

• Here, in the given question we have a bimetallic strip with one end attached to the wall rigidly so that it is in horizontal orientation.

• Upon heating the strip gains the temperature and expands horizontally along the length because it is fixed to the wall only from one end.