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Questions on Expansion and Contraction

 

Q8. Below is a diagram of a bimetallic thermometer

(a) From the diagram deduce which metal expands to the greater degree for a given temperature rise; metal A or metal B.

Metal B

(b) Explain how you reasoned your way to the answer.

When the temperature is higher the pointer will move to the right. That means that the cogwheel must have rotated clockwise. To cause that to happen the ratchet must push to the left. To make it do that the bimetallic strip will bend to the left, meaning metal B is the one that expands the most. (Max 2 marks)

(3 marks)