Question

If a bimetallic strip is heated it will

• A. Bend towards the metal with higher thermal expansion
• B. Not bend at all
• C. Twist itself into a helix
• D. Bend towards the metal with lower thermal expansion

Answer 1

The correct option is D

Bend towards the metal with lower thermal expansion

Explanation for correct option:

Option (D):

1. We know that metals undergo thermal expansion when their temperature is raised.
2. A bimetallic strip is a strip that is made up of two types of metals.
3. Coefficient thermal expansion is a characteristic property of solids that is unique to each type of metal
4. Hence, the two different types of metal in a bimetallic strip will have two different coefficients of thermal expansion.
5. Therefore, the metal with a higher thermal expansion rate will expand and bend more than the metal with a lower thermal expansion.
6. As a result, the bimetallic strip will bend towards the metal with lower thermal expansion.

Explanation for incorrect option:

Option (A):

1. The metal with a higher thermal expansion rate will expand and bend more than the metal with a lower thermal expansion.
2. Hence, the bimetallic strip will not bend towards the metal with higher thermal expansion.

Option (B):

1. We know that metals undergo thermal expansion when their temperature is raised.
2. Hence, the metals will expand and bend.

Option (C):

1. Coefficient thermal expansion is a very small quantity due to which the net change in length of the metals is not enough to make complete twists.
2. Thus, the formation of a helix is not possible.

Hence, option D is the correct answer.