Which type of heat transfer can occur in a vacuum?

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

Answer: (B)

In a vacuum, heat must move without any surrounding matter, so the only way energy can travel from one object to another is through radiation. Radiation uses electromagnetic waves and does not require a medium, so it can carry energy through empty space.

Conduction needs molecules to touch or bridge a material, transferring energy by collisions and vibrations, which isn’t possible across a vacuum. Convection relies on the movement of a fluid, which doesn’t exist in empty space. Evaporation is a surface process tied to a phase change, and while it can occur on a surface, the energy transfer across the empty space itself is still accomplished mainly by radiation.

So, the type of heat transfer that can occur in a vacuum is radiation.