A light source is any object that emits electromagnetic radiation within the visible spectrum or other areas of the electromagnetic spectrum.
- The Sun is the most important natural light source for life on Earth and emits a broad spectrum of electromagnetic radiation, including visible light.
- Celestial sources of light include our own Sun and other stars, planets, moons, asteroids, comets, and meteors.
- Natural sources of light include lightning, volcanoes and forest fires.
- Bioluminescent organisms that produce light include some species of fish, fireflies, glow-worms, and certain types of fungi, bacteria and algae.
- Human-made light sources of the simplest types include natural tars and resins, wax candles, oil lamps, and gas lamps.
- Modern human-made light sources include tungsten filament incandescent bulbs, which produce light by heating a filament inside a glass bulb.
- Halogen bulbs are a type of incandescent lamp that uses a halogen gas to improve efficiency and lifespan, and produce a bright, uniform light.
- Fluorescent lamps are non-incandescent sources of light that work by exciting a gas or vapour with electricity, which produces ultraviolet light that is converted into visible light by a phosphorescent coating on the inside of the tube. These lamps are highly efficient and long-lasting.
- An LED is a type of semiconductor device that emits light when an electrical current passes through it.
Related diagrams
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References
- https://en.wikipedia.org/wiki/Light#Light_sources
A light source is a natural or man-made object that emits one or more wavelengths of light.
- The Sun is the most important light source in our lives and emits every wavelength of light in the visible spectrum.
- Celestial sources of light include other stars, comets and meteors.
- Other natural sources of light include lightning, volcanoes and forest fires.
- There are also bio-luminescent light sources including some species of fish and insects as well as types of bacteria and algae.
- Man-made light sources of the most simple type include natural tars and resins, wax candles, lamps that burn oil, fats or paraffin and gas lamps.
- Modern man-made light sources include tungsten light sources. These are a type of incandescent source which means they radiate light when electricity is used to heat a filament inside a glass bulb.
- Halogen bulbs are more efficient and long-lasting versions of incandescent tungsten lamps and produce a very uniform bright light throughout the bulb’s lifetime.
- Fluorescent lights are non-incandescent sources of light. They generally work by passing electricity through a glass tube of gas such as mercury, neon, argon or xenon instead of a filament. These lamps are very efficient at emitting visible light, produce less waste heat, and typically last much longer than incandescent lamps.
- An LED (Light Emitting Diode) is an electroluminescent light source. It produces light by passing an electrical charge across the junction of a semiconductor.
- Made-made lights can emit a single wavelength, bands of wavelengths or combinations of wavelengths.
- An LED light typically emits a single colour of light which is composed of a very narrow range of wavelengths.