COLOR YOUR SHADOW

There are two ways to mix colours: additive and subtractive systems.

The first one is created by mixing colours from light sources, the second one by mixing colours from matters which absorb parts of the spectrum of the light. Each system has its own three primary colours.

Switching on all the three colored lamps, you will see that the panel is enlightened by a white light, which is the sum of the three colours red, green and blue.
By mixing light from The three colours will be magenta, cyan and yellow, the three primary colours of the subtractive synthesis.
Where the three shadows overlap two by two, you’ll get the three primary colours of the additive synthesis: red, green, blue (the colours of the lamps).
Where the three shadows overlap altogether you will get black, which is the absence of light.

PATHS OF LIGHT

You can see how light passes through transparent materials other than air. In particular, you will experience the laws concerning reflection and refraction.

Reflection occurs when light rays bounce back with the same angle, just like in mirrors. Refraction occurs when light rays change direction because they travel from one medium to a different one according to density. The denser the medium, the bigger the change in direction. The index of refraction is a way of measuring the speed of light in a material.

In a vacuum, light travels at 300,000 km/sec, but it slows down when it enters a medium. Generally speaking, in a medium, light “chooses” the faster path. In optics, this is called Fermat’s principle: the path taken between two points by a ray of light is the path that can be traversed in the least time.

Sometimes Fermat’s principle is described as the Baywatch principle. Imagine there’s a lifeguard on the beach who spots someone drowning sideways. His natural inclination is to take the quickest path towards that person, which is not a straight line. In fact, the best way is to run a bit further along the beach (where he goes faster) to shorten the distance through water and get to the person in trouble in the least time. So does the light: it takes the Baywatch route, arriving in the minimum time. An example is the straw that appears to be broken in a glass of water.

When light traveling in an optically dense medium hits a boundary at a steep angle (larger than the critical angle for the boundary), the light is completely reflected. This is called total internal reflection. This effect is used in optical fibers to confine light in the core. Light travels through the fiber core, bouncing back and forth off the boundary between the core and cladding.

PHOSPHORUS EFFECT

Your shadow will seem “stuck” to the panel.

The panel is coated with a phosphorescent substance that absorbs the light received and releases it afterwards for a few seconds.

If we cover a part of the panel with our body, its shape will remain on that part because that’s where the light couldn’t get through