8

Unit 8: Can You See the Light?

8.1 What is light?

Light has 3 main characteristics.

1. Light travels fast 
                                                   (300,000km/second)



2. Light travels in a straight line. 

3. Light can travel in all directions.

A light source is something that produces light.  

There are natural and artificial light sources. 

Natural sources are the sun and the stars.

Artificial sources include light bulbs, flash lights, and other electric light. .

8.2 Can you see through it?

There are some things that we can see through (like a window) and other things that we cannot (like a door).

Opaque:  light cannot pass through it.  (wood, stone, a door, a text book) 

Other things, like this window, are translucent (that means that only some light can pass through). 

Transparent means that all light can pass through, like this clear window! 

8.3 Can light change direction? 

Reflection: When light bounces off a surface and goes in a different direction.  

Shiny and smooth surfaces reflect light best. 

Refraction: when light passes through certain materials, it bends. 

Look how light is reflected in this laser art installation! It´s really amazing! 

8.4 Light and Colour!

Did you know that white light is actually made up of all the colours!?!

When you see a rainbow, the back of a CD, or a prism, you can  see the different colours of white light reflected!  

The three primary colours: yellow, red and blue

which can be mixed to form 

The secondary colours of: orange, green, and purple

This effect is called diffusion: when the white light gets spread out so we can see all its colours. Take a look at some of these everyday  examples of light diffusion!

Here´s a video to show you a bit more about light and colour!  Enjoy :)