Question

A bimetallic strip is made of aluminium and steel (${\alpha }_{steel}$ < ${\alpha }_{aluminium}$). On cooling down, the strip will:

• A. remain straight
• B. bend with aluminium on concave side
• C. get twisted
• D. bend with steel on concave side

Answer 1

The correct option is B bend with aluminium on concave side

Change in length of strips
$\Delta L=L_0\alpha \Delta T$
Since,
${\alpha }_{aluminium}>{\alpha }_{steel}$$\Rightarrow \Delta L_{aluminium}>\Delta L_{Steel}$
The decrease in length of aluminium strip is more as compared to that of the steel strip. So, the bimetallic stip will bend with aluminium strip on concave side.