Prism

What can you do here
 1. Direct the prism in such a manner that will allow you to observe a colourful stripe – it is the spectrum of the Sun’s light. If the Sun is hidden behind clouds, you can try observing the surrounding area looking through the prism. You should see the objects glowing around the edges. Notice the colour of light objects (benches, the nearby sport arena).

2. Rotate the prism slowly around its horizontal axis. At some angle you stop seeing things that are behind the prism, but instead you start seeing your own reflection, like in a mirror – you observe the effect of the total internal reflection.

How does it work
1. Sunlight is a mixture of waves of different length. Human brain perceives them as different colours (the longest wave is colour red, the shortest – violet), and their composition results in white. That is why we call sunlight the white light. The light, coming from the air through the prism and then into the air again, changes its direction – we say it refracts. The red light refracts the least, the violet – the most. The phenomenon of the white light dispersion is responsible for rainbow, where raindrops play the role of a prism. The colours of a rainbow are ordered from red in the upper part of the arch to violet inside the arch.

2. If the light strikes a medium boundary between surfaces at a proper angle it does not go through to the other material, but gets reflected. This phenomenon is called the total internal reflection. The boundary becomes a “mirror” in which we can see ourselves.

Interesting facts
The refractive index of diamond is extremely high, which is why diamond gemstones play unique light tricks.