Ampere [A]

The Ampere is the SI unit of electric current. Ampère's force law states that there is an attractive or repulsive force between two parallel wires carrying an electric current. This force is used in the formal definition of the ampere, which states that it is "the constant current that will produce an attractive force of 2 × 10–7 newton per meter of length between two straight, parallel conductors of infinite length and negligible circular cross section placed one meter apart in a vacuum

The SI unit of charge, the coulomb, is the quantity of electricity carried in 1 second by a current of 1 ampere.

It is named after André-Marie Ampère (1775–1836), French mathematician and physicist, considered the father of electrodynamics.

Current [A] = [W] / voltage [V] 



Illumination - Lux [lx]

The illuminance (E) describes the incident on a light reflective body energy. It is measured in lux (lx) and is calculated from the ratio of luminous flux and illuminated area. The light intensity can be measured with a light meter on horizontal and vertical surfaces. It depends on the reflection of light in the room and of the work that needs to be done.
Therefore, bright rooms require less illumination than dark.

The unit symbol for the illuminance is lux = lm / m².

Situation illuminance:

Situation Illuminance
Bright sunny day 100.000 lx
Cloudy summer day 20.000 lx
In the shade in the summer 10.000 lx
Cloudy winter day 3.500 lx
Elite football stadium 1.400 lx
TV studio lighting 1.000 lx
Office / room lighting  500 lx
Corridor lighting  100 lx
Street lighting  10 lx
Candle 1 meter away  1lx
Full moon  0,25 lx
Starry night sky (moon) 0,001lx 
Cloudy night sky without a moon and external lights 0,00013 lx


Color Rendering Index (CRI)

The Color Rendering Index (CRI) is the color rendering index (Ra) which is used for the characterization of light sources. This index reflects the naturalness of color. The higher the CRI, the more natural color
reproduction and the more comfortable they are perceived. The size of the CRI / Ra value can be between 0 and 100 and is essential for the color rendering of illuminated objects. 
Besides sunlight with an Ra index of 100, for example, energy-saving lamps have an Ra value of about 80 metal halide lamps bring it to a CRI value of 60 to 70, and white light-emitting diodes, W LEDs have a CRI
value of 80 An increase in the CRI value of W LEDs is achieved by "warm white" LEDs are lit, working with mostly two phosphors.
Those with high color rendering (HCR) working LEDs achieve CRI values
​​of up to 94.


Color temperature

Color temperature is the color profile of a completely black body, he reflected, when you heat it. Depending on the degree of heating of the black body only lights up red, yellow and blue. To specify the color temperature, use the number of Kelvin (K).


As a candle has a color temperature of 1,500 Kelvin, a 100-watt bulb temperature of 2,800 Kelvin, while the morning or evening sun is 5,000 Kelvin.


The color temperature is often also an influence on the spatial "mood." Thus, a space is illuminated with a color temperature of 2,000 Kelvin act quite differently than if the same space is illuminated with 6,500 Kelvin. Likewise, the color temperature can also have an impact on personal well-being and even feeling. Thus, a red wine taste different in a warm color temperature than with a bright cold white tone.


Light source Color temperature
Candle 1500 K
Sodium vapor lamp 2000 K
Bulb (40 W) 2600 K
Bulb (100 W) 2800 K
Halogen lamp (high voltage) 2700-2800 K
Halogen lamp (Low voltage) 3000-3200 K
Fluorescent (Cool White) 4000 K
Xenon lamp 4500–5000 K
Morning Sun / evening sun 5000 K
Morning / afternoon sun 5500 K
Overcast 6500–7500 K
Fog, heavy mist 7500–8500 K
Blue (cloudless) sky on the shaded north side of  9000–12.000 K
Just after sunset or just before sunrise 
Clear blue northern sky light  15.000–27.000 K


Life cycle

An outstanding feature of LEDs is their long life - as long as they are operated under certain conditions. In contrast to a conventional bulb LED not just suddenly falls off, but loses in the course of its operating time gradually in brightness. Depending on grade this brightness decrease is faster or slower.
As mentioned under "benefits" very high quality LEDs can have a lifecycle of over 80.000 – 120.000 hours (equivalent to 11 ½ years of continuous burn time) and longer (New calculations of LED manufacturer shows a possible lifecycle of 363.000 hours – 41,4 years non-stop) reach - always assuming that they are operated properly by the user. Proper use of LEDs means that the values ​​specified by the manufacturer when operating current and temperature are observed.
However, external factors such as moisture or weather conditions can greatly influence the lifetime of an LED.