5 °C Expansion of 100 mm Samples
Here is another example of how to think of thermal expansion. If we have a 100 mm (4 in) long sample of each of these materials, and change the temperature 5 °C (9 °F), the lengths will change as shown.
Twenty-five micrometers is about 0.001 inch. As you can see, the question "How close should my lab temperature be to 20 °C be?" depends a great deal upon what you are going to measure.
Note also there are two values for steel gage blocks (Steel GB) in the chart. One of the peculiarities of most steel gage blocks is that the CTE depends on the length of the block. We will discuss this more later.