Thermal expansion of solids – metal rods and a bimetallic strip

Integrated ScienceMatter & MaterialsAges 13–14

Three rods of aluminium, copper and steel with the same length are heated equally; a dial gauge at the end of each rod measures the increase in length ΔL = α·L₀·Δt to a hundredth of a millimetre. Students record a data table and see that aluminium expands the most and steel the least. In bimetallic strip mode, a copper–steel strip bends towards the steel (the metal that expands less) and breaks an electric circuit, like the thermostat in an electric iron.