furnace device

jimbo71

1. The problem statement, all variables and given/known data
see attachment


2. Relevant equations



3. The attempt at a solution
I do not understand the diagram.

Attached Thumbnails

 

Redbelly98

The two lines labelled AB are actually strips of two different metals, attached to each other (usally be welding them together, I think)

When the temperature changes, the metal strips curve or bend to the right and touch the thing in the upper right of the figure.

jimbo71

So, they expand and contract which is determined by the temperature from the heat given off from the furnace. Why are two different metals used?

mgb_phys

They expand different amounts with temperature and so bend - the bending amplifies the very small change in length.