Basic light theory

Expressions in the light theory:

Kelvin:
Temperature a black item needs, to reflect a certain colour

Nm:
Wavelength in the light spectra

Lumen:
Light intensity from a given light source

Lux:
Amount of light, per unit area, e.g. cm²

Ra-Index:
Distribution of light in the spectra, compared to normal daylight

 Sun light

JT electric

Light measured in LUX

A luxmeter measures light, like the human eye:

  • Sun light: > 100.000 lux
  • Overcast: 2.000 – 20.000 lux
  • Moon light: 1 lux
  • Office light: 400-500 lux

Basic light theory – in water

Colour temperature and Light in water:

Normal Metal Halide Lamp = 5.000 Kelvin
High pressure sodium lamp = 2.000 Kelvin

Blue light penetrates water best, because it has a lower wavelength
Yellow light has the poorest penetration of water, because it has higher wavelength

Reduction of light comparing to wavelength

reduction of light explained