What is an example of heat transfer by radiation?

Heat transfer by radiation occurs when energy is emitted as electromagnetic waves, which can travel through a vacuum and do not require a medium. The warmth felt from the sun is a prime example of this process, as solar radiation from the sun travels through the vastness of space and reaches Earth, where it warms the surface and the atmosphere.

In contrast, the other options describe forms of heat transfer that involve direct contact or conduction. Heating food on a stove and boiling water in a kettle involve conduction where heat is transferred through direct contact with hot cookware. Similarly, feeling heat from a campfire primarily involves convection and conduction as the heat travels through the air and warms nearby objects and individuals, but it is not an example of radiation. Therefore, the warmth felt from the sun is the only option that exemplifies heat transfer by radiation effectively.