ਫਰਮਾ:SI radiometry units
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ਇਸ ਹਿੱਸੇ/ਲੇਖ ਨੂੰ ਪੰਜਾਬੀ ਵਿੱਚ ਅਨੁਵਾਦ ਕਰਨ ਦੀ ਜਰੂਰਤ ਹੈ ਹੈ। ਤੁਸੀਂ ਇਸਦਾ ਪੰਜਾਬੀ ਵਿੱਚ ਅਨੁਵਾਦ ਕਰਕੇ ਵਿਕੀਪੀਡੀਆ ਦੀ ਮਦਦ ਕਰ ਸਕਦੇ ਹੋ। | 
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| Quantity | Unit | Dimension | Notes | |||||
|---|---|---|---|---|---|---|---|---|
| Name | Symbol[nb 1] | Name | Symbol | Symbol | ||||
| Radiant energy | Qe[nb 2] | joule | J | M⋅L2⋅T−2 | Energy of electromagnetic radiation. | |||
| Radiant energy density | we | joule per cubic metre | J/m3 | M⋅L−1⋅T−2 | Radiant energy per unit volume. | |||
| Radiant flux | Φe[nb 2] | watt | W or J/s | M⋅L2⋅T−3 | Radiant energy emitted, reflected, transmitted or received, per unit time. This is sometimes also called "radiant power". | |||
| Spectral flux | Φe,ν[nb 3] or Φe,λ[nb 4] |
watt per hertz or watt per metre |
W/Hz or W/m |
M⋅L2⋅T−2 or M⋅L⋅T−3 |
Radiant flux per unit frequency or wavelength. The latter is commonly measured in W⋅sr−1⋅m−2⋅nm−1. | |||
| Radiant intensity | Ie,Ω[nb 5] | watt per steradian | W/sr | M⋅L2⋅T−3 | Radiant flux emitted, reflected, transmitted or received, per unit solid angle. This is a directional quantity. | |||
| Spectral intensity | Ie,Ω,ν[nb 3] or Ie,Ω,λ[nb 4] |
watt per steradian per hertz or watt per steradian per metre |
W⋅sr−1⋅Hz−1 or W⋅sr−1⋅m−1 |
M⋅L2⋅T−2 or M⋅L⋅T−3 |
Radiant intensity per unit frequency or wavelength. The latter is commonly measured in W⋅sr−1⋅m−2⋅nm−1. This is a directional quantity. | |||
| Radiance | Le,Ω[nb 5] | watt per steradian per square metre | W⋅sr−1⋅m−2 | M⋅T−3 | Radiant flux emitted, reflected, transmitted or received by a surface, per unit solid angle per unit projected area. This is a directional quantity. This is sometimes also confusingly called "intensity". | |||
| Spectral radiance | Le,Ω,ν[nb 3] or Le,Ω,λ[nb 4] |
watt per steradian per square metre per hertz or watt per steradian per square metre, per metre |
W⋅sr−1⋅m−2⋅Hz−1 or W⋅sr−1⋅m−3 |
M⋅T−2 or M⋅L−1⋅T−3 |
Radiance of a surface per unit frequency or wavelength. The latter is commonly measured in W⋅sr−1⋅m−2⋅nm−1. This is a directional quantity. This is sometimes also confusingly called "spectral intensity". | |||
| Irradiance | Ee[nb 2] | watt per square metre | W/m2 | M⋅T−3 | Radiant flux received by a surface per unit area. This is sometimes also confusingly called "intensity". | |||
| Spectral irradiance | Ee,ν[nb 3] or Ee,λ[nb 4] |
watt per square metre per hertz or watt per square metre, per metre |
W⋅m−2⋅Hz−1 or W/m3 |
M⋅T−2 or M⋅L−1⋅T−3 |
Irradiance of a surface per unit frequency or wavelength. The terms spectral flux density or more confusingly "spectral intensity" are also used. Non-SI units of spectral irradiance include Jansky = 10−26 W⋅m−2⋅Hz−1 and solar flux unit (1SFU = 10−22 W⋅m−2⋅Hz−1). | |||
| Radiosity | Je[nb 2] | watt per square metre | W/m2 | M⋅T−3 | Radiant flux leaving (emitted, reflected and transmitted by) a surface per unit area. This is sometimes also confusingly called "intensity". | |||
| Spectral radiosity | Je,ν[nb 3] or Je,λ[nb 4] |
watt per square metre per hertz or watt per square metre, per metre |
W⋅m−2⋅Hz−1 or W/m3 |
M⋅T−2 or M⋅L−1⋅T−3 |
Radiosity of a surface per unit frequency or wavelength. The latter is commonly measured in W⋅m−2⋅nm−1. This is sometimes also confusingly called "spectral intensity". | |||
| Radiant exitance | Me[nb 2] | watt per square metre | W/m2 | M⋅T−3 | Radiant flux emitted by a surface per unit area. This is the emitted component of radiosity. "Radiant emittance" is an old term for this quantity. This is sometimes also confusingly called "intensity". | |||
| Spectral exitance | Me,ν[nb 3] or Me,λ[nb 4] |
watt per square metre per hertz or watt per square metre, per metre |
W⋅m−2⋅Hz−1 or W/m3 |
M⋅T−2 or M⋅L−1⋅T−3 |
Radiant exitance of a surface per unit frequency or wavelength. The latter is commonly measured in W⋅m−2⋅nm−1. "Spectral emittance" is an old term for this quantity. This is sometimes also confusingly called "spectral intensity". | |||
| Radiant exposure | He | joule per square metre | J/m2 | M⋅T−2 | Radiant energy received by a surface per unit area, or equivalently irradiance of a surface integrated over time of irradiation. This is sometimes also called "radiant fluence". | |||
| Spectral exposure | He,ν[nb 3] or He,λ[nb 4] |
joule per square metre per hertz or joule per square metre, per metre |
J⋅m−2⋅Hz−1 or J/m3 |
M⋅T−1 or M⋅L−1⋅T−2 |
Radiant exposure of a surface per unit frequency or wavelength. The latter is commonly measured in J⋅m−2⋅nm−1. This is sometimes also called "spectral fluence". | |||
| Hemispherical emissivity | ε | 1 | Radiant exitance of a surface, divided by that of a black body at the same temperature as that surface. | |||||
| Spectral hemispherical emissivity | εν or ελ |
1 | Spectral exitance of a surface, divided by that of a black body at the same temperature as that surface. | |||||
| Directional emissivity | εΩ | 1 | Radiance emitted by a surface, divided by that emitted by a black body at the same temperature as that surface. | |||||
| Spectral directional emissivity | εΩ,ν or εΩ,λ |
1 | Spectral radiance emitted by a surface, divided by that of a black body at the same temperature as that surface. | |||||
| Hemispherical absorptance | A | 1 | Radiant flux absorbed by a surface, divided by that received by that surface. This should not be confused with "absorbance". | |||||
| Spectral hemispherical absorptance | Aν or Aλ |
1 | Spectral flux absorbed by a surface, divided by that received by that surface. This should not be confused with "spectral absorbance". | |||||
| Directional absorptance | AΩ | 1 | Radiance absorbed by a surface, divided by the radiance incident onto that surface. This should not be confused with "absorbance". | |||||
| Spectral directional absorptance | AΩ,ν or AΩ,λ |
1 | Spectral radiance absorbed by a surface, divided by the spectral radiance incident onto that surface. This should not be confused with "spectral absorbance". | |||||
| Hemispherical reflectance | R | 1 | Radiant flux reflected by a surface, divided by that received by that surface. | |||||
| Spectral hemispherical reflectance | Rν or Rλ |
1 | Spectral flux reflected by a surface, divided by that received by that surface. | |||||
| Directional reflectance | RΩ | 1 | Radiance reflected by a surface, divided by that received by that surface. | |||||
| Spectral directional reflectance | RΩ,ν or RΩ,λ |
1 | Spectral radiance reflected by a surface, divided by that received by that surface. | |||||
| Hemispherical transmittance | T | 1 | Radiant flux transmitted by a surface, divided by that received by that surface. | |||||
| Spectral hemispherical transmittance | Tν or Tλ |
1 | Spectral flux transmitted by a surface, divided by that received by that surface. | |||||
| Directional transmittance | TΩ | 1 | Radiance transmitted by a surface, divided by that received by that surface. | |||||
| Spectral directional transmittance | TΩ,ν or TΩ,λ |
1 | Spectral radiance transmitted by a surface, divided by that received by that surface. | |||||
| Hemispherical attenuation coefficient | μ | reciprocal metre | m−1 | L−1 | Radiant flux absorbed and scattered by a volume per unit length, divided by that received by that volume. | |||
| Spectral hemispherical attenuation coefficient | μν or μλ |
reciprocal metre | m−1 | L−1 | Spectral radiant flux absorbed and scattered by a volume per unit length, divided by that received by that volume. | |||
| Directional attenuation coefficient | μΩ | reciprocal metre | m−1 | L−1 | Radiance absorbed and scattered by a volume per unit length, divided by that received by that volume. | |||
| Spectral directional attenuation coefficient | μΩ,ν or μΩ,λ |
reciprocal metre | m−1 | L−1 | Spectral radiance absorbed and scattered by a volume per unit length, divided by that received by that volume. | |||
| See also: SI · Radiometry · Photometry | ||||||||
- ↑ Standards organizations recommend that radiometric quantities should be denoted with suffix "e" (for "energetic") to avoid confusion with photometric or photon quantities.
- ↑ 2.0 2.1 2.2 2.3 2.4 Alternative symbols sometimes seen: W or E for radiant energy, P or F for radiant flux, I for irradiance, W for radiant exitance.
- ↑ 3.0 3.1 3.2 3.3 3.4 3.5 3.6 Spectral quantities given per unit frequency are denoted with suffix "ν" (Greek)—not to be confused with suffix "v" (for "visual") indicating a photometric quantity.
- ↑ 4.0 4.1 4.2 4.3 4.4 4.5 4.6 Spectral quantities given per unit wavelength are denoted with suffix "λ" (Greek).
- ↑ 5.0 5.1 Directional quantities are denoted with suffix "Ω" (Greek).
