- When (most) materials are heated, they expand
- This expansion happens because the molecules start to move around (or vibrate) faster, which causes them to knock into each other and push each other apart
Note: When this happens, it is the space taken up by the molecules that increases. The molecules themselves remain the same size.
Exam Question: What is Thermal Expansion?
- The thermal expansion of materials can have some useful applications, but also has some undesirable consequences
- The expansion of a liquid in a thermometer can be used to measure temperature
- A bimetallic strip, consisting of two metals that expand at different rates, can be made to bend at a given temperature, forming a temperature-activated switch
- The expansion of solid materials can cause them to buckle if they get too
- This could include:
- Metal railway tracks
- Road surfaces
- Things that are prone to buckling in this way often have gaps built into them providing some room for them to expand into