A student on a hiking trip wraps a steel water canteen in a wet cloth to keep the water inside cool on a dry, windy day.
Explain, in terms of molecules, how the evaporation of water from the wet cloth causes the temperature of the remaining water in the cloth to decrease.
As the wet cloth cools, thermal energy is conducted from the water inside the canteen through its steel wall. Explain how free electrons transfer thermal energy through the metal wall of the canteen.
528 exam-style questions on CIE IGCSE Physics 2.2 Thermal properties and temperature, covering 2.2.1 Thermal expansion of solids, liquids and gases, 2.2.2a Internal energy and temperature, 2.2.2b Specific heat capacity, 2.2.3a Melting, boiling, condensation and solidification, 2.2.3b Evaporation, and 2.2.3c Cooling by evaporation. Each one has a worked solution and a mark scheme showing where the marks go.