What is radiation?

What is radiation?

• A. Heat transfer by electromagnetic waves that does not require matter.
• B. Heat transfer by the movement of a fluid.
• C. Heat transfer by contact between objects.
• D. Heat transfer that requires matter.

Answer: (A)

Radiation is heat transfer by electromagnetic waves. These waves carry energy from a warmer object to a cooler one and can travel through empty space, so matter isn’t required for the heat to move. We feel this warmth from the Sun or a fire even when there’s air or other matter between us and the source. All heated objects emit some radiation, and the amount increases with temperature. In contrast, conduction needs direct contact with matter for energy to move from one object to another, and convection involves the bulk movement of a fluid (air or liquid) carrying heat with it. Radiation stands out because it can occur without any medium at all.

Radiation is heat transfer by electromagnetic waves. These waves carry energy from a warmer object to a cooler one and can travel through empty space, so matter isn’t required for the heat to move. We feel this warmth from the Sun or a fire even when there’s air or other matter between us and the source. All heated objects emit some radiation, and the amount increases with temperature.

In contrast, conduction needs direct contact with matter for energy to move from one object to another, and convection involves the bulk movement of a fluid (air or liquid) carrying heat with it. Radiation stands out because it can occur without any medium at all.