Which heat transfer method can occur in a vacuum?

Which heat transfer method can occur in a vacuum?

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

Answer: (A)

In a vacuum, there’s no material medium to carry heat by touching or by moving a fluid, so conduction and convection can’t occur. The only way heat can move across empty space is by radiation, which travels as electromagnetic waves. All objects emit thermal radiation based on their temperature, so heat can transfer from a hotter body to a cooler one through space without any matter in between. Evaporation involves a phase change of a liquid and is not a heat transfer method that operates across a vacuum by itself, whereas radiation does not require a medium. That’s why radiation is the correct choice.

In a vacuum, there’s no material medium to carry heat by touching or by moving a fluid, so conduction and convection can’t occur. The only way heat can move across empty space is by radiation, which travels as electromagnetic waves. All objects emit thermal radiation based on their temperature, so heat can transfer from a hotter body to a cooler one through space without any matter in between. Evaporation involves a phase change of a liquid and is not a heat transfer method that operates across a vacuum by itself, whereas radiation does not require a medium. That’s why radiation is the correct choice.