IGCSE Coordinated Science: Convection Convection 1. Recognise convection as the main method of heat transfer in ﬂuids. Fluids are often very poor conductors, but if they are free to circulate they can carry thermal energy through a process called Convection. 2. Relate convection in ﬂuids to density changes. Above is an example of a convection current. If the bottom is gently heated, as the water above the ﬂame becomes warmer, it expands and decreases in density. The less dense water rises as cooler, denser water
sinks and takes its place, or we can say, Displaces it. This is a convection current. However, convection does not occur if the water is heated at the top as warmer, less dense water will simply just stay at the top. 3. Describe experiments to illustrate convection in liquids and gases. Convection in Air Convection doesn’t only occur in liquids, they can also occur in gases. An example is the Convection Current in air. Heated by the sun, the warm air rises above the equator and cool air displaces the warm air. This results in a convection current in the earths atmosphere.
Room Heating Warm air rises above the heater or radiator, and it is displaced by cool air.