Sources of light

Light is a spectrum- meaning some light is visible

There are countless sources of light, but they can all be categorized under either of the two following categories-

Objects that emit light for example the sun, moon, stars and some living organism by bioluminescence.

Light can artificially be created under three BROAD categories

Incandescent sources- when certain objects are heated to a high temperature they emit light. Both infrared and visible light is produced. Ex. Candle.
Luminescent sources- produced by accelerating charges in a luminescent material, bypassing current through the material. Ex. Electric Bulb.
Gas discharge sources- when electricity passes through certain gases at low pressure. light is produced. Ex. Neon lamp.

Frequency: Number of waves that pass in a certain period of time

Wavelength: Distance between two corresponding points on adjacent waves

If the frequency is high, the wavelength is shorter. Whereas if the wavelength is bigger, f is lower

Speed of light is about 3.00 x 10^8m/s

Other types of light emission:

Fluorescence- emission of light from a substance that has absorbed light
Phosphorescence- energy absorbed by substances then released slowly, glow in the dark
Chemiluminescence- light is the product of a chemical reaction, two high energy chemicals break down to release light

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