A bimetallic strip is made of aluminium and steel αAl>αsteel. On heating, the strip will

1. remain straight

2. get twisted

3. will bend with aluminium on the concave side

4. will bend with steel on the concave side

(d) Hint: The amount of bending depends on the nature of the material.
Step 1: Find the amount of bending in the two materials.
As αAl>αsteal, aluminium will expand more. So, it should have a larger radius of
curvature. Hence, aluminium will be on the convex side.