# Light Energy| Sources, Examples & Facts

Light energy is a type of kinetic energy.

It was a fascinating thing for many scientists like Einstein, Faraday, and Maxwell etc.

Light is the only non-materialistic thing which is visible to naked eyes.

One can see, feel it as the heat but cannot hold it and contain it as such.

It travels from one place to other in the form of light rays till it loses its energy.

### Light energy facts:

1. Light is an electromagnetic energy; it means, the light rays have both electric and magnetic behavior in them.

This electromagnetic radiation can be divided in different ranges based on wavelength or frequency.

This spectrum has gamma rays, X-rays, ultraviolet rays, visible rays, infra red radiation, microwaves and radio waves in increasing order of wavelength.

2. Light Waves: Light travels in the form of waves. Each wave is characterized by its wavelength and frequency. Waves with greater energy have high frequency and small wavelength. While waves with low energy have low frequency with long wave length. But interestingly they all travel with same speed.

3. Speed of light: The speed of light is very high and may be the fastest thing ever. In figures it is 670,616,629 mph. And how could one calculate the speed of light and its history is interesting.

4. Light absorption: Light is absorbed by the substances it falls on. Most substances absorb the light rays to some extent and deflect remaining. When the light is absorbed, heat is generated in most objects. Hence the floor or surfaces exposed to sunlight are hot.

A substance which absorbs all of the light rays or energy is called as a black body. It is a hypothetical body and does no exist.

5. Photons of light: Light is thought to have energy packets called as photons. These are elementary particles of light and have wave nature and particle nature. The energy of a photon is given by Planck’s constant i.e. E = hf. (Where ‘E’ =energy, ‘h’= Planck’s constant and ‘f’= frequency of light).

6. Photosynthesis: When light falls on green leaves of plants, they convert it into chemical energy which is stored as carbohydrates. Not only sun, even if light from the electric bulbs at night falls on leaves, photosynthesis occurs.

7. Solar energy: The energy of light can be harvested by solar panels and used for domestic use. This alternative energy is environmental friendly and so many started to harvest it.

Sources of light:

1. Sun: Sunlight is the oldest source of light energy. This sunlight is essential for life on earth as it has many uses like water cycle, photosynthesis, sanitation and sterilization. Energy on the sun is generated due to hydrogen fusion. This light travels from sun around it and reaches the planets and other bodies around it including earth.

2. Electric bulbs: Electric bulbs are another source of this energy. When electricity flows through metallic filament tungsten in the bulb, it glows due to resistance. Due to resistance, the filament is so heated that it emits light.

3. Flame: When a fuel material is burnt, the flame produced emits light rays. So for night vision before discovery of bulb, lanterns and other fire emitting devices were used for illumination.

4. Explosions: When a powerful bomb is exploded, there is emission of light due to intense heat generation. When atomic bombs were tested, the entire regions were illuminated with intense light.
In above examples, energy of another forms is converted to energy ofÂ  light.

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