Thermal expansion of solids, liquids and gases Flashcards – Cambridge IGCSE (9–1) Physics 0972 (Extended) (2026–2028)

What is thermal expansion?

An increase in a substance’s dimensions when its temperature rises.

What generally happens to solids, liquids and gases when they cool at constant pressure?

They contract.

For a given temperature rise, how do solids, liquids and gases generally compare in thermal expansion?

Solids usually expand least, liquids more and gases most. The amount depends on the substance.

What does heating do to particle energy?

It increases particle energy.

How does heating cause a solid to expand?

Its particles vibrate more, increasing their average separation slightly.

What particle change generally causes a liquid’s volume to increase when heated?

The average separation between its particles increases.

How can heating cause a gas to expand at constant pressure?

Faster-moving particles exert pressure on the surroundings. If the gas can expand while pressure stays constant, its volume increases.

Why are gaps or expansion joints used in structures such as bridges?

They allow expansion without excessive stress.

What can happen to rails if their thermal expansion is restricted?

They can buckle.

How is thermal expansion used in a liquid-in-glass thermometer?

The liquid’s expansion is used to indicate temperature.

Why can overhead wires sag more in warm weather?

They expand as they warm.