Study Material

Light sources: types and devices that emit light

We explain light sources with types and devices that emit light. The light sources are those which emit electromagnetic radiation at wavelengths between 380 nm and 750 nm (nanometers), the band known as the visible spectrum, that is detectable by the sense of sight. different types of light sources

The main source of light for Earth is the Sun , followed by the Moon, the planets, and the stars. When artificial lights did not exist, if the nights were clear enough, the Milky Way would dimly illuminate the night, casting shadows on the ground.

Primary and secondary light sources

At some point, it is estimated that it was about 200,000 years ago, humanity discovered fire and with it the possibility of lighting the night, obtaining heat, warding off predators and carrying out activities. different types of light sources

In addition to the celestial bodies there are other sources of natural light, among which we can mention rays or lightning, which are of short duration, incandescent lava, and even animals and plants that are capable of emitting their own light.

Light is linked to high temperatures, electric shocks, and chemical reactions where combustion occurs. All these phenomena can be used to obtain a stable, durable and transportable light source, adjustable at will to illuminate interior spaces and facilitate nighttime activities. different types of light sources

Types of light sources

Light sources are classified in several ways. They can basically be:

-Primaries: they emit the light they produce.

-Secondary: they reflect the light produced by primary sources.

The Sun is the most familiar primary light source of all. The sun king, like all stars, produces large amounts of light and energy due to the reactions that occur in its nucleus.

Other primary sources are candles, torches, and lamps.

Instead, bodies that do not produce light by themselves must be illuminated to be seen. They reflect the light coming from the primary sources and are therefore called secondary light sources .

The Moon and planets like Venus , Mars, and Jupiter , for example, are secondary sources, since they reflect sunlight.

However, it should be noted that materials that do not produce light by themselves under normal circumstances, can become luminous under certain conditions, for example if they are heated: a metal heated to red hot emits light.

The sunlight

The Sun is undoubtedly the main source of light on Earth
The Sun is undoubtedly the main source of light on Earth

The Sun is the most important star for the Earth and the most studied of all. Thanks to the light and heat of the Sun, life develops on the planet, hence the star king aroused the interest of humanity since the beginning of history.

The Sun is a huge ball of gas, at the center of which high temperatures are reached to allow the fusion or conversion of hydrogen into helium, a process that generates a large amount of energy in the form of radiation.

To obtain a helium atom, four hydrogen atoms are required, but a small fraction of the present mass is converted into energy, according to Einstein’s famous formula E = mc 2 , where E represents energy, m is mass and c is speed. of light in emptiness. different types of light sources

This energy travels as an electromagnetic wave in a vacuum and contains various wavelengths, mainly in the range of visible light. But it also contains other lengths not perceptible to the human eye, such as infrared and ultraviolet.

Light emitting devices


Incandescent lamps have been the most widely used artificial light source in the world, despite being inefficient
Incandescent lamps have been the most widely used artificial light source in the world, despite being inefficient

The lamps made it possible to extend people’s working hours and contributed to safety on roads and cities. In the beginning, the first lamps made use of combustion, such as torches and candles. different types of light sources

The combustion materials used at different times depended on the resources that people had on hand: oil and wax, for example. This form of lighting lasted for a long time, until in the nineteenth century the design of lamps improved significantly, producing more intense light. By then, gas lamps were in common use in public lighting in major European cities.

The advent of electric light brought with it the development of lighting systems based on electricity and various light-emitting devices. different types of light sources

The fundamental principle is, as indicated at the beginning, to convert some kind of energy into light. For example, when atoms or molecules of certain substances go from a lower energy state to a higher one and then back to the ground state, photons are emitted , which are tiny packets of light energy.

There are a number of ways to get atoms to do this. The most convenient is to pass an electric current through the material, be it solid or gas. different types of light sources

Some of the most widely used lamps today, based on electricity, are described below. The two ways that light is emitted through the passage of current are incandescence and luminescence.

In the process of incandescence the atoms of the material are excited thanks to the increase in temperature caused by the current. On the other hand, in luminescence the energy is absorbed by the material and emitted again accompanied by photons.

  • Incandescent lamps

They consist of a transparent or colored glass bulb or capsule, and resistant to temperature, with a metal filament inside, usually tungsten, a very appropriate element thanks to its high melting point. Additionally the bulb is filled with an inert gas, such as argon, for example. different types of light sources

When the electric current passes through the filament, it heats it and it emits energy, most of it in the form of heat, but a small percentage of it is transformed into light.

Although they are easy to produce and their cost is affordable, they have low performance and for this reason they have been replaced for some time by other types of more efficient and durable lamps.

  • Halogen lamps

The principle of operation of halogen lamps is the same as that of the common incandescent bulb, only the interior is filled with a halogen gas, usually bromine. The addition of halogen gas greatly improves the performance of the lamp and prolongs the life of the filament.

  • Discharge lamps

They consist of a gas enclosed in a tube, whose particles are excited (change to a higher energy state) when current passes. When the electrons in the gas return to their original state, they emit light, the color of which depends on the gas used in the lamp.

Originally the current came from the discharge of a capacitor, hence the name given to this type of lamp.

  • Fluorescent lamps

They consist of a tube, which in addition to a mercury gas inside, contains a layer of material that also emits light by fluorescence, when its atoms are excited by the current.

The radiation emitted by mercury atoms when they return to their original state is almost all ultraviolet, however the coating of fluorescent material increases the emission in the visible light range, but its efficiency is greater than that of incandescent lamps. different types of light sources

  • Led lamps

They are built using light-emitting diodes, whose electrons are temporarily excited by the passage of current. When they return to their fundamental state, they emit intense light and of very good performance, which is why they are replacing traditional types of lamp.

The laser

It is a monochromatic light source, that is, of a single wavelength, unlike the sources previously described, which contain a variety of wavelengths. different types of light sources

The word “laser” is an acronym, formed by the initials of the name in English:  Light Amplification by Stimulated Emission of Radiation. The translation is “light amplification by stimulated radiation emission.”

Laser light is high- powered and can be handled to produce a variety of effects on matter , not just lighting. They are used in CD devices, for the transmission of information and in the field of health. different types of light sources

Other objects and materials that emit light

  • A flashlight.
  • A lighter.
  • A light bulb.
  • A bonfire.
  • A match.
  • A candle.

List of light sources

This is a list of light sources , which includes both natural and man-made processes that emit light. This article focuses on sources that produce wavelengths of about 390 to 700 nanometers called visible light .

Electric shock

  • Electric arc
    • Arc lamp
    • Flash lamp
  • Electrostatic discharge
    • Flash of lightning
    • Electric spark
  • Discharge lamp
    • Induction lamp
      • Sulfur lamp
    • Excimer lamp
    • Fluorescent lamp
      • Compact fluorescent lamp
      • Tanning lamp
      • Black lights
      • Geissler tube
      • Moore’s Lamp (disused)
      • Lamp “Ruhmkorff” (disused)
    • High intensity discharge lamp
      • Carbon arc lamp
      • Mercury vapor lamp
      • Metal halide lamp
      • Sodium vapor lamp
      • Xenon lamp
    • Hollow cathode lamp
    • Neon and argon lamps
      • Decatron (disused)
      • Nixie tube
    • Plasma lamp
    • Xenon flash lamp


  • Blackbody radiation
  • Carbon pellet lamp (disused)
  • Earthquake lights
  • Halogen lamp
  • Incandescent lamp
  • Wash
  • Nernst lamp (disused)
  • Volcanic eruption



  • Quinqué (in disuse)
  • Argon flash
  • Carbide lamp (disused)
  • Betty Lamp (disused)
  • Butter lamp
  • Flash lamp (deprecated)
  • Gas lighting
  • Incandescent shirt
  • Kerosene lamp
  • Limelight (deprecated)
  • Oil lamp
  • Tilley’s Lamp (disused)


  • Bunsen lighter
  • Candle
  • Embers
  • Explosives
  • Fire
  • Fireworks
  • Flamethrower
  • Rubens tube
  • Torch

Nuclear and high energy particles

  • Annihilation
  • Braking radiation
  • Cherenkov radiation
  • Cyclotron radiation
  • Fuser
  • Nuclear explotion
  • Cintillation
  • Synchrotron light source

Celestial and atmospheric

Nebula and stars
Starry sky, the Milky Way, and a shooting star
  • Astronomical objects
    • Sun ( sunlight , solar irradiation )
      • Solar corona
      • Photosphere
    • Stars ( starlight )
      • Nova / supernova / hypernova
      • Galaxies
        • Milky Way
      • Star clusters
    • Deep space objects
      • Quasars
      • Accrual discs
      • Blazares
      • Magnetars
      • Pulsars
  • Atmospheric reentry
    • Meteor shower
    • Racing cars
  • Lightning ( Plasma )
    • Red spectrum
    • Globular ray
    • Super-atmospheric discharge
    • Dry lightning
  • Polar aurora


Luminescence is the emission of light by a substance not resulting from heat.


Chemiluminescence is light resulting from a chemical reaction .


Bioluminescence is light resulting from the biochemical reaction of a living organism.

  • Aequorea victoria
  • Antarctic Krill
  • stomatopods
  • Foxfire
  • Fireflies
  • Luciferase
  • Panellus stipticus


Electrochemiluminescence is light resulting from electrochemical reactions .


Crystalluminescence is light produced during crystallization .

Electroluminescence different types of light sources

Electroluminescence is light resulting from an electric current that passes through a substance. different types of light sources

  • Light emitting diodes
  • Organic Light Emitting Diodes
  • Electromechanical light emitting cell
  • Electroluminescent wire
  • Electruminescent polymer induced by electric field
  • Lasers
  • LED lamp


Cathodoluminescence is light resulting from a luminescent material being hit by electrons.

Mechanoluminescence different types of light sources

Mechanoluminescence is light resulting from a mechanical action on a solid.

  • Triboluminescence
  • Piezoluminescence
  • Sonoluminescence

Photoluminescence different types of light sources

Photoluminescence is light resulting from the absorption of photons

  • Fluorescence
  • Phosphorescence

Radioluminescence different types of light sources

Radioluminescence is the light resulting from bombardment by ionized radiation.

Thermoluminescence different types of light sources

Thermoluminescence is the light resulting from the re-emission of absorbed energy when a substance is heated.

Cryoluminescence different types of light sources

Cryoluminescence is the emission of light when an object is cooled. different types of light sources

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