radiation
The emission or transmission of energy in the form of waves or particles through space or a material medium.
Unlike conduction and convection, radiation does not require any physical medium (like solid, liquid, or gas) to travel; it can propagate through the absolute vacuum of space.
Word relationships
- emission: Emission is the general act of sending out something, while radiation specifically refers to energy traveling outward in waves or rays.
- absorption: Absorption is the taking in of energy, which is the direct opposite of radiating or emitting it.
Commonly confused with
- radioactivity: Radiation is the energy emitted in waves (including light and heat), whereas radioactivity is the spontaneous decay of unstable atomic nuclei.
Word family
- radiate (verb): To emit energy in the form of rays or waves.
- radiant (adjective): Emitting heat or light.
Collocations
- thermal radiation
- electromagnetic radiation
- solar radiation
- radiation heat transfer
Example sentences
- "The Earth receives vital thermal energy from the sun entirely through electromagnetic radiation." Astrophysics explanation of solar energy
- "Thermal radiation becomes the dominant mode of heat transfer at extremely high temperatures." Scientific paper on thermal management
Memory hook
Think of a classic steam radiator in an old apartment, radiating heat outward in all directions like rays of light. Rays of heat through empty space.
When not to use
Do not limit this term only to dangerous nuclear radioactivity; in thermodynamics, it primarily refers to harmless infrared thermal radiation.
Fun facts
- Your own body constantly radiates heat; in a cool room, a human body emits about 100 watts of thermal radiation, which is equivalent to an old incandescent light bulb.
Related words
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