Question

When a bimetallic strip is heated, it

• A. does not bend at all
• B. bends in the form of an arc with the more expand−able metal inside
• C. gets twisted in the form of a helix
• D. bend in the form of an arc with the more expandable metal outside

Answer 1

The correct option is D bend in the form of an arc with the more expandable metal outside

Now here the both strips are attached and there is difference in their coefficients.
More the expansion coefficient more its length will grow.

In this case ${\alpha }_A>{\alpha }_B$
So, strip will bend forming concavity on $B$ side.
A bimetallic strip on being heated bends in the form of an arc with more expandable metal $\left(A\right)$ outside (as shown in the figure).
Final answer (c)