Physics – 2.3.2 Convection | e-Consult

Convection is the transfer of thermal energy through the movement of fluids (liquids and gases). This movement is caused by differences in density that arise due to temperature variations. When a fluid is heated, it expands, becoming less dense. This less dense, warmer fluid then rises, while the cooler, denser fluid sinks to take its place. This creates a circular current known as a convection current.

In liquids and gases, this process is particularly effective. The rising warm fluid carries thermal energy with it, transferring it to cooler regions. The sinking cool fluid brings cooler temperatures to the bottom, and then warms up as it rises. This continuous circulation efficiently distributes heat.

Example: The heating of water in a pot on a hob is a classic example of convection. The hob heats the water at the bottom of the pot. This heated water becomes less dense and rises. Cooler water from the top sinks to the bottom to be heated, creating a convection current that distributes heat throughout the water.