Category Science

How is nuclear energy produced?

               Nuclear energy is produced by changes in the nucleus of the atom of a radioactive element such as uranium or plutonium. This process is called nuclear fission. The nucleus is split by bombarding the atom with a neutron particle. Each time the uranium atom is split in this way, it releases energy. It also produces three more neutrons, which then go on to split other uranium atoms. This is called a chain reaction because, once started, it will continue the process of nuclear fission while releasing very large amounts of energy.

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How does radar work?

 

               Radar works by sending out a beam of high- frequency radio waves, which are reflected back when they strike a solid object. The radio waves can also be reflected by clouds or other weather features. The reflected waves are collected and used to produce an image. Usually the radar beam is emitted from a rotating scanner, so a complete 360° image is produced. Radar is important in the navigation of ships, aircraft, and weather forecasting.

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What are silicon chips?

               

               A silicon chip is a tiny wafer of silicon (a semiconductor) on which a complete electronic device can be produced. An image is produced photographically and etched onto the chip, but it differs from a printed circuit in some important ways. The chip is often microscopically small and contains huge amounts of ‘wiring’. More importantly, part of the process allows other devices to be produced in the manufacturing process, such as tiny resistors and capacitors. So a silicon chip, or integrated circuit, which measures just a few millimeters across, is a complete electronic device.

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What is a printed circuit?

               Any modern electrical device requires a huge number of connections to join together all the small components needed for it to work effectively. At one time these connections were made by wires that had to be soldered together. The wires have now been replaced by the printed circuit, which is effectively a picture of the wiring that works just as well.

               A thin sheet of copper is attached to a special board made of insulating material. An image of the electrical circuit is then printed photographically onto the copper sheet. Chemicals are used to dissolve most of the copper, leaving behind a thin film of metal bands, to which all the necessary components can be attached. This process can be carried out automatically.

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How does radio communication work?

               Radio signals are transmitted using a carrier wave. A radio transmitter changes, or modulates, this radio wave in order to convey information. In AM radio the height of the carrier wave is altered according to the sound picked up by a microphone. In FM radio the frequency, or distance between the peaks in the radio wave, is changed. The radio receiver picks up these signals and amplifies and decodes them. If the signal is weak, AM radio sounds crackly. It is now being replaced by FM radio, which gives much clearer reception.

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