SafekipediaRadiant energy
Adapted from Wikipedia · Adventurer experience
In physics, radiant energy is the energy carried by electromagnetic and gravitational radiation. We measure it in joules (J), just like other kinds of energy. Scientists use the symbol Qe for radiant energy, where "e" means “energetic.”
Radiant energy can be found by adding up the radiant flux, or power, over a certain time. This shows us how much energy is moving through waves or particles. Radiant energy is important in many natural and technological processes, whether the radiation is visible light or a type we cannot see.
Terminology use and history
The term "radiant energy" is used in fields like radiometry, solar energy, heating, and lighting. It can also be used in telecommunications. In technology, "radiant energy" means electromagnetic waves that move power from one place to another.
Radiant energy includes gravitational radiation. The first gravitational waves ever observed came from black holes crashing together.
Analysis
Radiant energy is the energy carried by light and other types of waves. We can think of it as tiny packets of energy called photons or as waves that move through space. Both ways help us understand how energy travels.
When these waves hit something, they can warm it up. For example, sunlight makes the ground hotter. This can happen with many kinds of waves, not just the ones we see. Waves can also bounce off objects or spread out.
Radiant energy helps move energy into and out of things, like how solar panels use sunlight to make electricity or how the Earth gets warm from the Sun. The Sun creates this energy through a powerful process inside it.
Applications
Radiant energy is used to heat spaces. It can be made with electric infrared lamps or come from sunlight to warm water. The heat comes from a warm surface, like a floor or wall, and warms people and objects directly, not the air. This can make a room feel comfortable even if the air is cooler.
Radiant energy has many other uses, such as checking and inspecting things, separating items, and sending messages. These uses need a source of radiant energy and a detector that senses the radiation and changes it into an electric signal or another form, like making photographic film show an image.
SI radiometry units
| Quantity | Unit | Dimension | |||
|---|---|---|---|---|---|
| Name | Symbol | Name | Symbol | ||
| Radiant energy | Qe | joule | J | M⋅L2⋅T−2 | |
| Radiant energy density | we | joule per cubic metre | J/m3 | M⋅L−1⋅T−2 | |
| Radiant flux | Φe | watt | W = J/s | M⋅L2⋅T−3 | |
| Spectral flux | Φe,ν | watt per hertz | W/Hz | M⋅L2⋅T −2 | |
| Φe,λ | watt per metre | W/m | M⋅L⋅T−3 | ||
| Radiant intensity | Ie,Ω | watt per steradian | W/sr | M⋅L2⋅T−3 | |
| Spectral intensity | Ie,Ω,ν | watt per steradian per hertz | W⋅sr−1⋅Hz−1 | M⋅L2⋅T−2 | |
| Ie,Ω,λ | watt per steradian per metre | W⋅sr−1⋅m−1 | M⋅L⋅T−3 | ||
| Radiance | Le,Ω | watt per steradian per square metre | W⋅sr−1⋅m−2 | M⋅T−3 | |
| Spectral radiance Specific intensity | Le,Ω,ν | watt per steradian per square metre per hertz | W⋅sr−1⋅m−2⋅Hz−1 | M⋅T−2 | |
| Le,Ω,λ | watt per steradian per square metre, per metre | W⋅sr−1⋅m−3 | M⋅L−1⋅T−3 | ||
| Irradiance Flux density | Ee | watt per square metre | W/m2 | M⋅T−3 | |
| Spectral irradiance Spectral flux density | Ee,ν | watt per square metre per hertz | W⋅m−2⋅Hz−1 | M⋅T−2 | |
| Ee,λ | watt per square metre, per metre | W/m3 | M⋅L−1⋅T−3 | ||
| Radiosity | Je | watt per square metre | W/m2 | M⋅T−3 | |
| Spectral radiosity | Je,ν | watt per square metre per hertz | W⋅m−2⋅Hz−1 | M⋅T−2 | |
| Je,λ | watt per square metre, per metre | W/m3 | M⋅L−1⋅T−3 | ||
| Radiant exitance | Me | watt per square metre | W/m2 | M⋅T−3 | |
| Spectral exitance | Me,ν | watt per square metre per hertz | W⋅m−2⋅Hz−1 | M⋅T−2 | |
| Me,λ | watt per square metre, per metre | W/m3 | M⋅L−1⋅T−3 | ||
| Radiant exposure | He | joule per square metre | J/m2 | M⋅T−2 | |
| Spectral exposure | He,ν | joule per square metre per hertz | J⋅m−2⋅Hz−1 | M⋅T−1 | |
| He,λ | joule per square metre, per metre | J/m3 | M⋅L−1⋅T−2 | ||
| See also: | |||||
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