Quick questions on Methods of heat transfer in cooking - O-Level Food and Nutrition

Conduction is the transfer of heat from particle to particle through a solid or by direct contact. When a pan sits on a hob, heat is conducted through the metal into the food touching it. Metals are good conductors, which is why pans and woks are made of metal, while wood and plastic are poor conductors (insulators), which is why spoon handles and oven gloves are made of them.

Convection is the transfer of heat by the movement of currents in a liquid or a gas. When a fluid is heated, the hot part becomes less dense and rises, while cooler, denser fluid sinks to take its place. This sets up a circulating convection current that carries heat around the food.

Radiation is the transfer of heat as rays (infra-red) that travel directly from a hot source to the food, without needing any material in between. The food absorbs the rays and heats up.

Many cooking methods use more than one type of transfer. Baking a cake uses convection currents of hot air plus conduction from the hot tin, and some radiation from the oven walls. Recognising the main mechanism helps explain how a method cooks and how to control it.