Colouring outside the lines…

  Colours are amazing – a world without colour would be truly uninspiring. We even describe something that is depressing or unimpressive “grey” or “colourless”. But what is colour, scientifically speaking? Well, for a start, red is not made up of red waves – colour is a response of the human eye to a specific range of frequencies. The part of the electromagnetic spectrum that can be perceived by the human eye as colour is called the visible light spectrum:

Colours themselves are interesting, but what happens when they interact with each other is even more interesting. Colours can either be added (light from two different sources interact) or subtracted (light passes through a filter or reflects of a coloured surface).

                                                                                         

The first picture (left) shows what happens when you add colours, the second (right) shows what happens when you subtact colours by allowing them to pass through a series of filters. Here is a link to a flash application to investigate colour addition – play with it and see what colours you can generate (can you make orange, for example?).

Here is a video showing how colours can interact:

 

 

 

And here is a second video showing a similar experiment

 Finally, here is an excellent documentary, in six parts, giving a great roundup of a lot of the physics and engineering behind light effects in the modern world. (Part 1, Part 2, Part 3, Part 4, Part 5, Part 6). Here are the board notes from our lesson, and here are the next section of class notes

Three more links:

1. Colour Survey - Try it – you think you know what blue is, don’t you…
2. Results from the Colour Survey: Only for the hardcore geeks amongst you.
3. Java Applets on Colour – you are expected to use these. Get to it!

See you in class.

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