Units of Light - Maple Programming Help

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Units of Light

 

Description

Examples

Description

• 

Luminous intensity is a base dimension in the International System of Units.  The SI unit of luminous intensity is the candela,  which is defined as the luminous intensity, in a given direction, of a source that emits monochromatic radiation of frequency 5.41014 hertz and that has a radiant intensity in that direction of 1/683 watt per steradian (16th CGPM, 1979).

• 

Luminous flux has the dimension luminous intensity solid angle. The SI unit of luminous flux is the lumen, which is defined as a candela steradian.

• 

Luminous luminance has the dimension luminous intensity per length squared. The SI composite unit of luminous luminance is the candela per meter squared.

• 

Illuminance has the dimension luminous intensity solid angle per length squared.  The SI unit of illuminance is the lux, which is defined as a candela steradian per square meter.

• 

Maple knows the units of light listed in the following table.

Name

Symbols

Context

Alternate Spellings

Prefixes

 

 

 

 

 

candela

cd

SI *

candelas

SI

carcel

 

standard *

carcels

 

Hefner_unit

HK

standard *

Hefner_units

 

 

 

 

 

 

lumen

lm

SI *

lumens

SI

 

 

 

 

 

nit

 

standard *

nits

 

lambert

Lb

standard *

lamberts

SI

footlambert

ftLb

standard *

footlamberts, feetlambert

 

skot

 

standard *

skots

 

stilb

 

standard *

stilbs

 

apostilb

asb

standard *

apostilbs

 

 

 

 

 

 

lux

lx

SI *

lux

SI

footcandle

 

standard *

footcandles, feetcandle

 

nox

 

standard *

 

 

phot

 

standard *

phots

 

candle

 

international

candles

 

 

 

standard

 

 

  

An asterisk ( * ) indicates the default context, an at sign (@) indicates an abbreviation, and under the prefixes column, SI indicates that the unit takes all SI prefixes, IEC indicates that the unit takes IEC prefixes, and SI+ and SI- indicate that the unit takes only positive and negative SI prefixes, respectively.  Refer to a unit in the Units package by indexing the name or symbol with the context, for example, candela[SI] or lx[SI]; or, if the context is indicated as the default, by using only the unit name or symbol, for example, candela or lx.

  

 

  

The units of light are defined as follows.

Luminous Intensity

  

A carcel is defined as 10 candelas.

  

A Hefner unit is approximately 0.903 candela.

Luminous Flux

  

The only unit of luminous flux is the lumen.

Luminous Luminance

  

A nit is defined as a candela per square meter.

  

A stilb is defined as a candela per square centimeter.

  

A lambert is defined as 1π candela per square centimeter.

  

A footlambert is defined as 1π candela per square foot.

  

An apostilb is defined as 0.0001 lambert.

  

A skot is defined as 1.10-7 lambert.

Illuminance

  

A phot is defined as a kilolux.

  

A nox is defined as a millilux.

  

A footcandle is defined as a lumen per square foot.

Examples

mapconvert,'cd','lm','cd''m'2,'lx','dimensions','base'=true

luminous_intensity,luminous_intensitylength2lengthradius2,luminous_intensitylength2,luminous_intensitylengthradius2

(1)

mapconvert,'cd','lm','cd''m'2,'lx','dimensions','base'=true,'symbolic'=true

luminous_intensity,luminous_intensity,luminous_intensitylength2,luminous_intensitylength2

(2)

convert23,'units','stilb','cd''m'2

230000

(3)

convert100.0,'units','cd''m'2,'apostilb'

314.1592654

(4)

convert1,'units','footcandle''foot'2,'lumen'

1

(5)

convert1.0,'units','phot','lux'

10000.0

(6)

convert1.0,'units','nox','lux'

0.001000000000

(7)

See Also

convert/dimensions

convert/units

Units

Units/Index

Units/length

Units/solid_angle

 


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