###### Asked in Math and ArithmeticArea

Math and Arithmetic

Area

# How many lux are there in an area of 25 square meter?

## Answer

###### Wiki User

###### August 07, 2013 5:47AM

On a very dark night, nearly none.

## Related Questions

###### Asked in Home Electricity

### How do you calculate a lux level in a room?

Light Level or Illuminance, is the total luminous flux incident
on a surface, per unit area. The work plane is where the most
important tasks in the room or space are performed.
Measuring Units Light
Level - Illuminance
Illumenance is measured in foot candles (ftcd, fc, fcd) (or
lux in the metric SI system). A foot candle is
actually one lumen of light density per square foot,
one lux is one lumen per square meter.
1 lux = 0.0929 foot candle = 1 lumen /sq meter = 0.0001
phot
1 ftcd = 1 lux / 10.752
1 lumen/sq ft = 1 foot candle = 1x104 lux = 1 phot

###### Asked in Physics, Planet Mars, Darvon and Darvocet

### How many candelas equals 1 lux?

They really aren't equal because they measure two different
things. However, they are related to each other.
The Candela is the measure of the luminous intensity of a
light source. A higher Candela number means a brighter light. Lux
is a measurement of light density and means lumens per
square meter. Again, a greater number of lux means that the surface
being illuminated by the light is is receiving more light per
square meter.
The formula for calculating the conversion of candelas to lux is
E = I/(D*D) where E is the Illuminance of the
the surface in lumens per square meter (lux), I is the
Intensity of the the light source in Candelas and of course
(D*D) is the square of the distance from the light source in
meters.
Therefore 1 Candela will illuminate a surface with 1 Lux
only at one meter from a light source. At different
distances it will illuminate to different densities of light.
For example: Solving for E, that same one candela light
source would only read 1/4 lux at two meters [ 1/(2*2)] and 1/16
lux at four meters [1/(4*4)].
If you know the lux at a given distance in meters from the light
source you can solve for I and it will give you the
intensity of the light in Candelas. From that you can calculate the
intensity of the light.
For example: Solving for I, multiply the lux times the
square of the distance in meters and you will have the intensity of
the light source in Candelas.
So a reading of 8 lux at a distance of 3 meters would mean that
the light source has an intensity of 8*3*3 or 72 candelas.

###### Asked in Renewable Energy, Solar Power

### How do you find out lumen from lux?

There's not a direct conversion, but both are based on the
candela, a unit of luminous intensity. There is a nice explanation
of the difference between lumens and lux at
http://en.wikipedia.org/wiki/Lumen_(unit).
Lumens is the total amount of light a light source (a light
bulb, for instance) throws in all directions. Lux (lumens per
square meter) can measure how intense light from that light source
is when looking toward it from a certain distance. Lux depends
greatly on how far away you are from a light source. At any given
instant, light is thrown from the source in a perfect sphere.
If you are trying to calculate how many lumens your light bulb
shines and you have a light meter that gives you lux, point your
meter at the light, then take your lux multiply by 12.57 (pi times
4). Then, multiply this by the distance of your light meter from
the light bulb (in meters) squared. That will give
you the lumens of the light bulb. In equation form, where lm is
lumens, r is your distance from the light source, and pi is (come
on) about 3.14, lux=lm/(pi*4*(r^2)), or lm=lux*pi*4*(r^2). The
(pi*4*(r^2)) part is used to calculate the surface area of a sphere
around the light source.
Note: this calculation does not account for reflected light, and
will only work on an exposed light bulb. Lights housed in a
reflective cone (like in a flashlight) are designed to project
light in one direction and (within the spot where light is
projected) will have a lux much higher at any given distance than
if the light bulb wasn't housed in a cone.
Answer
A lux is a special name given to a lumen
per square metre. To convert lux to lumens, you need to
multiply the illuminance (light arriving) on a surface, in lux, by
the area of that surface, in square metres.

###### Asked in Digital Cameras, Cameras, Photography

### What is unit of illumination?

Illumination is usually measured in foot candles, lux or lumens.
Foot candles are measured one foot from the light source, whereas
lumens are measured at a distance of one square meter. To convert
from lumens to foot candles requires converting from square meters
to square feet. Foot candles x 10.76 = number of lux.

###### Asked in Science, Home Electricity, Solar Power

### How convert LUX to Lumens?

Lumens is the total amount of light a light source (a light
bulb, for instance) throws in all directions. Lux (lumens per
square meter) can measure how intense light from that light source
is when looking toward it from a certain distance. Lux depends
greatly on how far away you are from a light source. At any given
instant, light is thrown from the source in a perfect sphere.
If you are trying to calculate how many lumens your light bulb
shines and you have a light meter that gives you lux, point your
meter at the light, then take your lux multiply by 12.57 (pi times
4). Then, multiply this by the distance of your light meter from
the light bulb (in meters) squared. That will give you the
lumens of the light bulb. In equation form, where lm is lumens, r
is your distance from the light source, and pi is (come on) about
3.14, lux=lm/(pi*4*(r^2)), or lm=lux*pi*4*(r^2). The (pi*4*(r^2))
part is used to calculate the surface area of a sphere around the
light source.
Note: this calculation does not account for reflected light, and
will only work on an exposed light bulb. Lights housed in a
reflective cone (like in a flashlight) are designed to project
light in one direction and (within the spot where light is
projected) will have a lux much higher at any given distance than
if the light bulb wasn't housed in a cone.

###### Asked in Inventions, Photography

### Who invented the lux meter?

Lux meter is a term sometimes used to refer to
a light meter. If you mean who invented the light meter, Weston
marketed the first photographic selenium meter in 1932, which was
not well received. Dr. Bruno Lange is also credited with inventing
a much more practical version in 1933 and started a company that
year. I believe both of these versions were exposure meters and not
designed to simply measure illumination. The meter has gone through
various improvements for which patents have been granted for, thus
there is more than one inventor of a light meter (Joseph Hostetter
applied for a patent for a type of light meter in 1974).
Lux is the metric version of the Imperial
measurement called foot candle, which is based on the level of
visible light at a point that is one foot away from one candle and
spread out over one square foot. Although lux was a known quantity
much earlier than the invention of the meter, would not be until
the use of modern materials made light measurement possible using
electronic means.

###### Asked in Shopping, Physics

### How luxmeter measure light intensity?

A luxmeter is equipped with an electronic eye. This eye takes in
light and converts it into an electric signal, passing it on to a
computer which calculates the data sent from the luxmeter and
converts it into lux.
1 lux is approximately the amount of light generated from a
regular candle 1 meter away. A full moon on a clear night is
0.27-1.0 lux and direct sunlight can vary from 32000 to 120000
lux.

###### Asked in Physics

### How many footcandle is 1 candela per meter square?

Foot Candela is the measuring unit for illuminance while
candela/meter squared is a measuring unit for luminance,which makes
conversion not possible. conversion can be done for units of the
same quantity, for example, illuminance units : ft candela = 10.764
lux. To know the difference between luminance & illuminance,
you can take a look at
http://www.tpub.com/content/gsacriteria/gsa_courtroom_lighting/gsa_courtroom_lighting0012.htm