Consequences of thermal energy transfer — Explain

Explain (a) why kitchen pans are designed the way they are, and (b) how a radiator heats a room by convection.

(a) Pans are made with a metal body because metals are good thermal conductors, so heat passes quickly and efficiently from the heat source through to the food; handles are made of plastic or wood, which are poor conductors, to prevent heat reaching and burning the user's hand. (b) A radiator heats the air in contact with it; this air expands, becomes less dense, and rises, while cooler, denser air sinks to take its place, setting up a convection current that circulates warm air around the room.