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When we enter a completely dark room, we cannot see anything around us, but the moment we switch on the light, everything is visible to us. This is because light can be detected with the help of human eye. Light is a form of energy which helps us to see things around us. Without light, we cannot see an object.
How does light help to make things visible?
When light rays fall on the object, it will get reflected, and when it enters our eye, we can see the object.
Sources of Light:
The objects which can emit light are known as light sources. There are two sources of light.
- Natural sources of light
- Artificial sources of light
Natural sources of light:
- The source which emits light naturally is known as natural sources of light. The Sun is the primary and the major source of natural light in our solar system.
- Some living organisms such as fireflies, jellyfish, glow-worm, certain deep-sea plants and some microorganisms have the ability to produce light, and this phenomenon is called as bioluminescence. It is due to the effect of certain chemical reactions occurring in the organism.
Artificial sources of light:
The source which emits light artificially is known as artificial source of light.
Some of the artificial sources of light are flame of a candle, incandescent lamp, neon lamp, Sodium lamp, etc. Artificial sources of light can be classified into three categories, they are,
- Incandescent sources
- Gas discharge sources
- Luminescent sources
Incandescent sources:
When certain objects are treated with a high temperature, they begin to emit light.
Example:
The glowing of hot iron rod and the red burners on an electric stove.
Luminescent sources:
Certain materials can produce light by accelerating the charges in them. One common way of doing this is bypassing current through the conducting material.
Example:
Fluorescent tube light, electric bulb
Gas discharge sources:
Light can be produced when we pass electricity through certain gases at very low pressure.
Example:
Neon lamp, Sodium lamp
Reference:
Image credits
https://commons.wikimedia.org/wiki/File:Neonlamp3.JPG
https://pixabay.com/photos/tunnel-glass-futuristic-light-4874650/
https://pixabay.com/photos/candle-flame-citronella-candlelight-1691572/
https://pixabay.com/photos/forest-sun-sunrise-light-rays-fog-704230/
https://pixabay.com/photos/night-fireflies-street-lights-road-4347523/
https://pixabay.com/photos/tunnel-glass-futuristic-light-4874650/
https://pixabay.com/photos/candle-flame-citronella-candlelight-1691572/
https://pixabay.com/photos/forest-sun-sunrise-light-rays-fog-704230/
https://pixabay.com/photos/night-fireflies-street-lights-road-4347523/
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