Color White light is not a single color; it is made up of a mixture of the seven colors of the rainbow. We can demonstrate this by splitting white light with a prism: This is how rainbows are formed: sunlight is “split up” by raindrops.

The colors of the rainbow: Red Orange Yellow Green Blue Indigo Violet Remember: Roy G. Biv !!!

Light from the Sun The light from the sun contains a grand mixture of electromagnetic waves of varying frequency (i.e. wavelength) The spectrum of light is characteristic of the TEMPERATURE of the sun!

Wavelengths of Light Red Light – l = 680 nm Green Light - l = 500 nm Blue Light - l = 470 nm

Adding colors White light can be split up to make separate colours. These colours can be added together again. The primary colours of light are red, blue and green: Adding blue and red makes magenta (purple) Adding blue and green makes cyan (light blue) Adding red and green makes yellow Adding all three makes white again

Only red light is reflected Seeing color The colour an object appears depends on the colors of light it reflects. For example, a red book only reflects red light: Homework White light Only red light is reflected

(or red and blue, as purple is made up of red and blue): A pair of purple pants, in addition to being ugly, would reflect purple light (or red and blue, as purple is made up of red and blue): Purple light A white hat would reflect all seven colors: White light

Using colored light If we look at a colored object in colored light we see something different. For example, consider the outfit below – I mean, from a physics standpoint, not as a fashion choice: Shirt looks red White light Shorts look blue

In different colors of light this kit would look different: Red light Shirt looks red Shorts look black Shirt looks black Blue light Shorts look blue

Using filters Red Filter Filters can be used to “block” out different colours of light: Red Filter Magenta Filter