Which term describes energy that can move through empty space without a medium?

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

Answer: (A)

Radiation is the form of energy transfer that can move through empty space without a medium. It doesn’t require matter, so it can travel through the vacuum of space—the Sun warms Earth this way. Conduction needs contact with nearby matter, as energy moves through particles colliding or electrons transferring energy. Convection relies on the bulk movement of a fluid carrying energy. Heat is the general term for energy in transit due to a temperature difference and can be transferred by all three mechanisms, but the ability to travel through empty space specifically points to radiation.