Q. Heat transfer that does not require a medium is called

The correct answer is: a) Radiation

Explanation:

Heat transfer

Heat transfer can occur in three primary ways: conduction, convection, and radiation.

– Conduction requires a medium (solid, liquid, or gas) for heat to transfer through direct contact between particles.
– Convection also requires a medium, typically a fluid (liquid or gas), where heat is transferred through the movement of the fluid itself.
– Radiation, on the other hand, does not require a medium. It is the transfer of heat through electromagnetic waves, such as infrared radiation. This is how the Sun’s heat reaches the Earth through the vacuum of space, where no medium exists.

Thus, the type of heat transfer that does not require a medium is radiation.