Question

A bimetal made of copper and iron strips welded together is straight at room temperature. It is held vertically so that the iron strip is towards the left hand and copper strip is towards right hand. The bimetal strip is then heated. The bimetal strip will :
(${\alpha }_{cu}=16.6\times {10}^{-}6/K$ and ${\alpha }_{fe}=12.0\times {10}^{-}6/K$)

• A. remain straight
• B. bend towards right
• C. bend towards left
• D. have no change

Answer 1

The correct option is C bend towards left

Copper strip will elongate more than the iron strip sue to ${\alpha }_{Cu}>{\alpha }_{Fe}$
Since the strips are welded together, the combined strip will bend towards left ( towards iron ) since copper strip will have more length than the iron strip.