Certified Fire Investigator Practice Exam

What does "Radiation" refer to in terms of heat transfer?

1. Heat transfer through direct contact between materials

2. Heat transfer through chemical reactions

3. Heat transfer by way of electromagnetic energy

4. Heat that is felt by humans without conduction

The correct answer is: Heat transfer by way of electromagnetic energy

Radiation refers specifically to the transfer of heat via electromagnetic energy. This process occurs without the need for any physical medium, meaning heat can be transferred through a vacuum, such as space. When energy is emitted as electromagnetic waves, it can be absorbed by objects, leading to an increase in temperature. In contrast, the other choices describe different modes of heat transfer. Heat transfer through direct contact between materials refers to conduction. The mention of chemical reactions relates to processes that typically involve different forms of energy transfer but are not primarily about heat transfer. Lastly, while heat felt by humans without conduction might seem related, it does not distinctly capture the concept of radiation as it implies sensations rather than the underlying physical principle of energy transfer through waves. Hence, choice C accurately defines radiation in the context of heat transfer.