1. A magnet falling through a copper pipe
The magnet induces an electric current in the copper pipe, which in turn produces a magnetic field. This magnetic field has an opposite orientation to the magnetic field of the magnet, and so the magnet is repelled, causing it to fall more slowly.
2. Making elephant’s toothpaste
When potassium iodide is added to hydrogen peroxide it causes it to break down into oxygen and water. When the two are combined with soap, the oxygen becomes trapped within the soapy water to form bubbles, producing a thick foam. This chemical reaction is exothermic, meaning it also produces heat, and so the foam created is hot.
3. The disappearing spoon
Gallium is a metal that melts in temperatures around 30 degrees Celsius. So if you stir a cup of room temperature water with a gallium spoon, it will slowly disappear.
4. Liquid nitrogen explosion
Super-cold liquid nitrogen is poured into a drinks bottle, the cap is screwed on and then the bottle is placed in a bin full of warm water, with 1,500 ping pong balls placed on top. As the liquid nitrogen warms up, it becomes a gas, which requires much more room. This causes it to burst out of the bottle in a big explosion, sending the ping pong balls flying everywhere.
5. Relight my fire
When you light a candle, the flame vaporises the surrounding wax for create heat and light. If you blow the handle out, the smoke that is given off still contains some of that vaporised wax, so if you ignite it, it will send a flame back down to the wick.
6. Gravity-defying slinky
If you watch a slinky being dropped in slow motion, the bottom of the spring appears to hover in mid-air. This is because, as it falls, the bottom of the spring has two forces acting upon it; gravity pulling it downwards, and the tension of the coils pulling it upwards. These two forces cancel each other out, causing the bottom of the spring to not move at all.
7. A solid liquid?
Non-newtonian fluids, such as quicksand, become more viscous when under stress, and so thicken up to become a solid. This is because they are made of much lager molecules than regular liquid which don’t have time to move around when they’re deformed very quickly. Therefore, if you gently place your hand in the liquid, it will behave as normal, but if you punch it, it will act like a solid. You can make your own non-newtonian fluid at home by mixing some cornstarch with water.
8. Bending water
When a negatively charged object is placed near to a stream of water, it repels some of the electrons in the water. This creates a positive charge in the stream so it is attracted towards the object. This desire to transfer electrons pulls the positively charged water toward the comb when it’s nearby. The force that attracts the two together is called static electricity.
9. Collapsing tanker
Normally, a tanker is able to keep it shape because the air pressure inside matches that of the surrounding air. If you remove the air from inside the tanker using a vacuum pump, the surrounding air pressure becomes much greater, and is able to crush the tanker like a drinks can.
10. Exploding colour
Pur some milk onto a plate and then pour some food colouring on top, being careful not to stir them together. Dip a cotton bud in washing up liquid and dab it in the centre of the plate. The soap reduces the surface tension of the milk by dissolving the fat molecules within it. The surface of the milk outside the soap drop has a higher surface tension, so it pulls the surface away from that spot. The food coloring moves with the surface, streaming away from the soap drop. As the soap becomes evenly mixed with the milk, the action slows down and eventually stops.
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