Follow us on twitter @OVLMagazine Find us on Facebook OVL Magazine 59 This little experiment will take you back to medieval China as we make one of the first ever compasses. For this you will need: 1. a cork from a bottle 2. a small pebble 3. a large needle 4. a rubber band 5. a small bowl 6. a magnet 7. a spoon 8. some water Take the needle and magnetise it by drawing one end of the magnet along its length. Repeat this about 30 times.Take the spoon and see if the needle is attracted to it. If not, continue rubbing until it is. Next place the needle on one side of the cork and the pebble on the other and hold them in place using the rubber band. Finally half fill the bowl with water and place the cork into it. You have made yourself a Chinese compass. Now take the magnet and move it close to the bowl. You should see the cork move. Finally take the bowl outside. If you walk and turn gently you should see the needle pointing in the same direction. Happy exploring! Thousand-Year-Old Compass L i t t l e Einsteins ’ C o r n e r Faraday’s many groundbreaking experiments at the Royal Society in London. Starting with the electromagnetic rotation of a wire around a magnet, he then went on to develop the first electric motor and the electric dynamo. He also went on to show how electricity flowing in a coil could induce a current in a second coil through magnetism. He later went on to discover that certain materials are diamagnetic such that they are weakly repelled by a magnetic field. But probably his greatest contribution to the understanding of magnetism was when he showed that a magnetic field could change the plane of polarisation of polarised light. Hence by the late 1860s it was understood that electricity and magnetism were opposite sides of the same coin. The idea of electric and magnetic fields which changed with time, and which interacted to create a resultant force had been proven beyond doubt. Around the same time, prompted by Faraday’s observations into how magnetism affected light, an as yet unknown Scottish scientist and mathematician James Clerk Maxwell started to work on the idea of an electromagnetic wave. He postulated that light was essentially the result of an oscillating electric field which was counterbalanced by an oscillating magnetic field perpendicular to it. The unexpected outcome from this theoretical work was that the electromagnetic wave was shown to move at the speed of light. It linked the physical phenomena of magnetism and electricity to radio waves, visible light and x-rays. This revelation formed the basis of Albert Einstein’s theory of Special Relativity as well as the Magnetic Quantum Number which is fundamental to Chemistry. At present the hunt is on for an elementary particle called a Magnetic Monopole which in essence should display the attributes of a single magnetic pole in isolation. So the story of magnetism is not over yet. Magnetism is a common phenomenon which typically occurs weakly in nature and affects our everyday life. Most of our technology relies on some aspect of magnetism, from fridges to mobile phones. The Earth’s magnetic field has protected our planet from being ravaged by particles ejected by the Sun, allowing life to take hold. It seems we owe our very existence to the giant magnet we are living on, so it’s no surprise we have been fascinated by the magic of magnetism since ancient times.