Refraction & Magnetism

In this episode of Beakman’s World, a bent looking straw sends Beakman into an explanation of refraction, the way light bends whenever it crosses from one material into another. A vanishing coin, a pair of borrowed glasses and a magnetised needle floating in a bowl of water carry the show from bending light to magnetism, ending with the biggest magnet of all, the planet Earth.

In this episode you will discover:

• Why a straw looks bent as soon as it touches water
• How a hidden coin can reappear just by adding water to a dish
• Why glasses use lenses to help correct blurry vision
• What is actually happening inside a piece of magnetised iron
• Why only iron, nickel and cobalt can become magnets
• How Earth’s core turns the whole planet into a giant magnet

Invisible Rules, Visible Effects

Refraction and magnetism both work by an invisible rule that only shows itself through a visible effect. Light does not actually bend the straw sitting in a glass of water, it bends itself, travelling at different speeds through air and water and pivoting the moment it crosses the boundary between them, which is also exactly why a coin hidden from view can suddenly reappear once water is added to its dish. Magnetism works the same way. Inside a piece of iron sit countless tiny magnetic domains pointing every which way, invisible until something lines them all up, and the same invisible alignment reaches all the way down into the planet itself, where a churning core of liquid iron quietly points every compass needle toward the north.

Beakman’s demonstrations

Beakman starts small, sliding a coin into a dish until it is hidden from view, then pouring in water until it reappears as if by magic, purely because the light carrying its image now bends up into the audience’s eyes. He borrows Ray’s glasses to show how lenses correct blurry vision, then switches gears entirely, stroking a needle against a magnet fifty times until its scattered internal domains line up into one strong pull, enough to attract a chain of paperclips and even levitate one off the desk. The segment ends with a globe sliced open to reveal a hidden bar magnet inside, proving that a compass needle turns exactly the same way no matter where it sits on the model, just as it does on the real, magnetic Earth.

Try this at home

The vanishing coin test. Place a coin in the bottom of a shallow dish or bowl and position your eye so the rim of the dish just hides it from view. Without moving your head, ask someone to slowly pour in water. The coin will seem to rise into sight even though it has not moved at all, because the water bends the light carrying its image up toward your eyes.

The compass test. Stroke a sewing needle along a magnet in the same direction fifty times, always lifting the magnet away and starting from the same end rather than rubbing back and forth. Rest the needle in a small boat cut from aluminium foil and float it in a bowl of water. Once the water settles, the needle will swing around to point north, lined up with Earth’s own magnetic field. Handle the needle carefully, as the point is sharp.

The crushed can test. With an adult, heat a tablespoon of water inside an empty drinks can over a stove until it is steaming well, then use tongs to plunge the can quickly into a bowl of cold water, opening downward. The trapped steam cools and shrinks almost instantly, and the ordinary air pressure outside crushes the can flat before you can blink.