Light, Lumen, Lux, Candela, Luminance Concepts.

What is Light?

Light is the name given to electromagnetic waves that spread in linear waves. Light and all other electromagnetic waves fundamentally have three properties:

• Frequency: It is inversely proportional to wavelength; the human eye perceives this property as color.
• Intensity: Also referred to as amplitude, it is perceived by the human eye as brightness.
• Polarization: This is the angle of vibration and is generally not detected by the human eye under normal conditions.

Since light exists in wave form, it has a certain frequency value. The color of light changes according to its frequency. The human eye can see colors between red and violet. If the frequency of light increases further, it goes beyond our vision limit and is called ultraviolet light. Conversely, if the frequency decreases to a level lower than red, it is called infrared light.

For example, when a television remote control works, it emits infrared light. We cannot see this with the naked eye, but if we look through a smartphone camera, we can see the light at a frequency that is invisible to the human eye.

Light is the phenomenon that enables living beings to see by reflecting off objects after it exits a light source or directly reflecting.

Objects that can be seen by spontaneously emitting light are called light sources.

The wavelength of visible light ranges from 380 nm to 760 nm. In the electromagnetic spectrum, this area is situated between infrared and ultraviolet.

What do Lumen, Lux, Candela, and Brightness mean, and what are the differences between them?

The terms Lumen, Lux, Candela, and Brightness refer to units of illumination.

Regarding the illumination units lm, lx, cd, and cd/m2;

• Ø – Light Flux – Lumen (lm) is the total amount of light produced in all directions by a light source. It is the measure of light flux and indicates the light power of the fixture.
• I – Light Intensity – Candela (cd) indicates the amount of light coming to any point in a specific direction from a light source. It is the measure of light intensity and is measured from a single point.
• E – Illuminance – Lux (lx) (lm/m2) shows the amount of light flux reaching a one-square-meter surface. It is the measure of the light level in an environment and is measured from the environment.
• L – Brightness – (Cd/m2) is the light intensity that reaches the eye from a unit area. In other words, it is the light intensity per square meter.