Optics For Kids - What is Light?

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What is Light?

It's a kind of energy called "electromagnetic (EM) radiation" (but this kind of radiation is not harmful, except for an occasional sunburn). There are other kinds of EM radiation too (radio waves, microwaves, x-rays, etc.), but light is the part WE can see, the part that makes the rainbow.

What is light?

How does light travel? FAST and STRAIGHT

Light only takes 8 minutes!
Light travels straight


About 186,000 miles per second [300,000 kilometers per second], so light from the sun takes about 8 minutes to go 93 million miles [149 million kilometers] to earth. Does this seem SLOW? Well, if you could DRIVE to the sun at 60 mph [100 kph], it would take you 177 years to get there! In one second, light can go around the earth 7 times!


Perfectly straight, until something bends it. The straight paths of light are called LIGHT RAYS.

Controlling Light

Block light

Block it

... with an object or person. 

This makes a shadow.

Reflect light

Reflect it

(change its path with a mirror) This is called a REFLECTION.

See this YouTube demo on light reflection

Bend light

Bend it

Change its direction by making it pass into another transparent material of different density, like glass or water. This is called REFRACTION, and it's how lenses work. There are actually other ways to bend or deflect light, including diffraction gratings and holographic lenses. Scientists have also found that gravity can bend light!

View "Bending Light" demo from the University of Colorado Boulder


Light is produced, controlled, and detected in so many ways around you!

Put your cursor over a picture to see what it is