Bimetallic Strip with Liquid Nitrogen

The bimetallic strip shown is made up of brass and stainless steel, with the brass having the higher thermal expansion coefficient. Brass is on the left in the images. Placed in liquid nitrogen (77K) and over a laboratory burner (T=?), the strip bends in opposite directions. 所示的双金属条由黄铜和不锈钢组成，其中黄铜的热膨胀系数更高。图片中黄铜位于左侧。当将其置于液氮（77K）中，并置于实验室火焰上方（温度为？）时，该条会向相反方向弯曲。

Note that the strip bends more when placed over the burner than when placed in the liquid nitrogen. This implies that the temperature of the flame is further above room temperature than the liquid nitrogen is below it, if the expansion coefficient is the same. Note the frost which forms on the bimetallic strip when it is first placed above the flame.