Heat transfer by direct contact between a hot object and a cooler object is called?

• A. Conduction
• B. Convection
• C. Radiation
• D. Induction

Answer: (A)

Direct contact heat transfer is called conduction. When a hotter object touches a cooler one, energy moves from the hot to the cold object through collisions and interactions of particles, and in metals, free electrons carry energy quickly between them. This is why a metal spoon warms up when placed in hot liquid—the heat travels through the spoon by conduction. Materials differ in how well they conduct: metals are good conductors, while wood or plastic are poor conductors (insulators).

The other ways heat can move don’t require direct contact. Convection involves the movement of a fluid carrying heat with it, such as warm air circulating. Radiation transfers heat through electromagnetic waves and can occur through empty space, like the sun warming the Earth. Induction refers to heating generated by changing magnetic fields, not by direct contact between objects.