In a technical sense, it is really not appropriate to refer to light as being coloured.

Light is simply a wave with a specific wavelength or a mixture of wavelengths; it has no colour in and of itself. An object that is emitting or reflecting light to our eye appears to have a specific color as the result of the eye-brain response to the wavelength.

So technically, there is really no such thing as yellow light. Rather, there is light with a wavelength of about 590 nm that appears yellow. And there is also light with a mixture of wavelengths of about 700 nm and 530 nm that together appears yellow. The yellow appearance of these two clearly different light sources can be traced to the physiological and psychological response of the eye-brain system, and not to the light itself.

So to be technically appropriate, a person would refer to “yellow light” as “light that creates a yellow appearance.” Yet, to maintain a larger collection of friendships, a person would refer to “yellow light” as “yellow light.”

There are LOTS OF FLIPPED CLASSROOM RESOURCES IN THIS WIKI THAT ARE DIRECTLY RELATED TO THIS TOPIC

There are LOTS OF 'LIGHT' SCIENCE ACTIVITIES IN THIS WIKI THAT ARE DIRECTLY RELATED TO THIS TOPIC

• IF UNABLE TO ACCESS YOUTUBE VIDEO (requires Flash) TRY: Can blind people see colour

Most people may think that this answer is silly, but this is not a trick question. Check out the videos below and see if they change your mind about the way you previously understood colour. Source: Youtube or PureView

• IF UNABLE TO ACCESS YOUTUBE VIDEO TRY VIEWPURE: This is not yellow (short)

• IF UNABLE TO ACCESS YOUTUBE VIDEO (requires Flash) TRY:How we see colour

Colour Addition (Interactives)

• http://www.physicsclassroom.com/Physics-Interactives/Light-and-Color/RGB-Color-Addition
• http://www.physicsclassroom.com/Physics-Interactives/Light-and-Color/RGB-Color-Addition/RGB-Color-Addition-Interactive