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Light


Light is a form of energy which our sense of sight can detect. It is made of electro-magnetic radiation and travels in a straight line. Red, green and blue are the primary colors of light. Mixing them in various ways will make all other colors, including white. 










The speed of light

The speed of light is the speed at which light travels. It is about 300,000 kilometres per second. Nothing travels faster than light. Wow, that's fast! When light travels through matter, like air or water, it slows down some, but it's still pretty fast.


To give you and idea as to how fast light is, we'll give you some examples:



The sun is almost 150 million km from the Earth. It takes around 8 minutes for light to get from the sun to the Earth. 
 
It takes around 1.3 seconds for light to go from the moon to the Earth.






Light helps us to survive


Without sunlight our world would be a dead dark place. Sunlight does more than just help us see (which is pretty great, too). Sunlight keeps the Earth warm, so it's not just a frozen ball in outer space. It also is a major component in photosynthesis which is how most of the plant life on Earth grows and gets nutrients. Sunlight is a source of energy as well as a source of vitamin D for humans.

Refraction 

Normally, light travels in a straight path called a ray, however, when passing through transparent materials, like water or glass, light bends or turns.

One example of refraction is a prism.
Prisms are unique in that each color of light is refracted to a different angle.

Lenses use refraction to help us see things. Telescopes help us to see things far away and microscopes enable us to see very small things. Even glasses use refraction so that we can see everyday things more clearly.


Now play and learn: