A room is cooled by an air conditioning unit located near the ceiling. When thermal energy is transferred through the air by convection, what happens to the density of the air when it is cooled and how does this cooled air move?
The density increases and the cooled air moves downwards.
The density increases and the cooled air moves upwards.
The density decreases and the cooled air moves downwards.
The density decreases and the cooled air moves upwards.
301 exam-style questions on CIE IGCSE Physics 2.3 Transfer of thermal energy, covering 2.3.1a Thermal conductors and thermal insulators, 2.3.1b Explaining thermal conduction, 2.3.2 Convection, 2.3.3a Thermal radiation, 2.3.3b Surface colour and texture, 2.3.3c Rate of emission and absorption of radiation, and 2.3.4 Consequences of thermal energy transfer. Each one has a worked solution and a mark scheme showing where the marks go.