The correlated colour temperature (CCT) is a specification of the colour appearance of the light emitted by a lamp, relating its colour to the colour of light from a reference source when heated to a particular temperature, measured in degrees Kelvin (K).
|Warm White/Golden Yellow
|Cool White/Pearl White
'Colour Rendering Index' or CRI is a measure of how well a light source can project the colour of objects accurately. It helps to compare the effect of the light source to how the object will actually appear in natural light or an ideal light source.
Natural sunlight has the greatest CRI of 100. The higher the CRI of a light source, the more natural are the colours seen under them. The scale of measurement ranges from 0-100.
The amount of power consumed by a bulb to produce light is defined as a 'Watt'. Greater the watts of a bulb, the greater is the power taken up by the light source.
The amount of light emitted from any light source is defined as 'Lumens' (lm). The higher the lumens for a light source, the greater light it produces.
The efficiency of light sources is measured by the amount of lumens emitted per watt of power consumed by the source and is measured by lm/W. The greater the lm/W, the greater is the efficiency of the light source.
For example, some LEDs give out the same light as incandescent bulbs but consume lower watts. Hence, their efficiency is greater compared to incandescent bulbs.
The bottom part of an LED contains a heat sink. This sink helps to dissipate heat that is built up in an LED. Heat management in an LED is crucial for optimal performance and to ensure longevity.
If an LED does heat up at the base, this is a sign of it being in good working condition.
The lux (symbol: lx) is the SI unit of illuminance and luminous emittance, measuring luminous flux per unit area. It is equal to one lumen per square meter. In photometry, this is used as a measure of the intensity, as perceived by the human eye, of light that hits or passes through a surface.
In AC circuits, the power factor is the ratio of the real power that is used to do work and the apparent power that is supplied to the circuit. The power factor can get values in the range from 0 to 1. When all the power is reactive power with no real power (usually inductive load) - the power factor is 0.