Magnets, smart cities and computers
Slide a ring magnet down a pencil that stands upright. Slide a second ring magnet on, turned so that like poles face each other. The second magnet repels the first and floats above it! If you turn it over, unlike poles meet and the magnets stick together. Engineers use this idea in a maglev train. Maglev means magnetic levitation. Powerful magnets lift the train a little above its track and push it along, so nothing rubs on the track. The ride is smooth and quiet and the train can be very fast, but maglev lines are expensive to build. A new smart city is being built in Egypt. Smart means it uses technology and sensors to help with services such as traffic and safety. A computer is a smart tool too, and it has main parts. An input device, such as a keyboard or a mouse, puts information in. The processor is like the brain: it follows instructions. Memory holds the work the computer is doing now. Storage keeps programs and files for a long time. An output device, such as a screen or a speaker, shows or plays the result. Never use small strong magnets near young children, who might swallow them.
Floating magnets, with a grown-up. Stand a pencil upright in a lump of modelling clay. Slide one ring magnet down onto the clay. Then slide a second ring magnet on, without letting them touch, and watch what happens. Turn the second magnet over and try again. Draw what you see and write what you notice. Remember the poles. Keep magnets away from phones, cards and screens, and never put them near your mouth. Next, sort the parts of a computer into input and output. Finally, write one new technology you would like to see in a smart city, and why.