Question

A bimetallic strip is made of two metal strips $A$ and $B$, having coefficient of linear expansions ${\alpha }_A$ and ${\alpha }_B$ . If ${\alpha }_A>{\alpha }_B$, which of the following describes the behaviour of the bimetallic strip when heated?

• A. It will bend but will not elongate.
• B. It will bend with the strip $A$ on the outer side.
• C. It will bend with the strip $B$ on the outer side.
• D. No bending at all.

Answer 1

The correct option is B It will bend with the strip $A$ on the outer side.

We know that,
Thermal expansion in length is given by
$\Delta L=L_o\alpha \Delta T$
Given,
${\alpha }_A>{\alpha }_B$
$\therefore \Delta L_A>\Delta L_B$


So, this unequal expansion will cause the strip to bend with metal $A$ on the outer (convex) side.