Can you walk along the curved line with the binoculars? It’s not easy. Left is right and right is left.
That’s because there are triangular glass blocks in the binoculars. We call these prisms. When beams of light fall on a prism, the light “breaks”. That means that the light bends. The bent light goes into your eye. Your brain doesn’t realise that it’s bent. It thinks light can only go straight ahead, so the light is coming from the other side. Which is why you see your right foot through the left prism and vice versa. Weird, isn’t it?
Something similar happens with water. Suppose there’s a coin in a bath. The light that bounces off the coin breaks at the surface of the water and then goes into your eye. If you try to pick up the coin, you miss because your brain thinks the light is coming from somewhere else.
Normally:
With prismoculars:
Light refraction for climbers
Sometimes climbers wear prism glasses. The prisms in the glasses break the light from above heading for their eye. So they can see what is happening above them without having to constantly turn their head up. It saves them some neck pain.
Light refraction for rainbow colours
What colour is sunlight? Do you think it’s white? That’s right! Do you think it’s another colour? Then you’re a bit right, as well!
That white sunlight is actually a mixture of all colours. The famous physicist Isaac Newton discovered that when he was playing with his prisms. A prism like this can break the white light up into all the colours of the rainbow.