Lux (lx) is the unit of illumination in the International System of Units (SI). It measures the amount of light energy incident on a given surface. Lux is therefore a measure of the illuminance or intensity of light on a specific area.
What exactly is Lux?
- Definition :
- 1 lux is equal to 1 lumen per square meter . A lumen (lm) is the unit of light output of a light source, and lux measures the distribution of that light over a surface.
- Formula :
- Lux (lx) = Lumen (lm) / Surface area (m²)
So, if you spread 100 lumens over an area of 10 square meters, the illuminance is 10 lux.
How does Lux work?
Lux depends on two things:
- The amount of light emitted by a light source (lumen).
- The size of the illuminated area .
- Higher lux values mean more intense illumination , while lower lux values indicate less illumination on a surface.
Example of Lux:
- A typical living room might have lighting of around 100 lux .
- A desk for working or reading often needs between 300 and 500 lux to work comfortably.
- Daylight can reach 10,000 lux or more, depending on location and time of day.
Lux and lighting:
Lux indicates how much light actually falls on a surface. This is important for various applications:
- Living areas : Lighting in living areas should be adequate for comfort and visibility.
- Offices : Lighting levels for workspaces are often recommended to be between 300 and 500 lux for a good working environment.
- Photography and videography : In photography, lux is often measured to determine the lighting conditions of a scene.
- Outdoor Lighting : Street lighting is often measured in lux to ensure there is sufficient illumination for safety.
Difference between Lux and Lumen:
- Lumen (lm) is a measure of the amount of light emitted by a source, without taking into account how this light is distributed over a surface.
- Lux (lx) measures the amount of light actually falling on a surface , taking into account the size of that surface.
So, for example:
- A lamp that emits 1000 lumens will deliver more lux over a smaller area and less over a larger area.
Lux standards for different applications:
- Living areas : 100-300 lux.
- Offices : 300-500 lux (depending on the task).
- Production work : 500-1000 lux, depending on the precision of the work.
- Specific workplaces (such as laboratories) : 1000 lux or more.
Conclusion:
Lux is the measure of illuminance on a given surface and indicates how much light actually falls on that surface. It is essential for determining the right lighting for various applications, from homes to workplaces and outdoor lighting, and helps create the right lighting conditions for comfort and productivity.