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Waves Waves can be described as a transfer of energy. They can occur in one, two or three dimensions, depending on the nature of the wave and medium. Waves can be classified as either mechanical or electromagnetic. Mechanical waves require a medium and can be either transverse or longitudinal. Electromagnetic waves do not require a medium and are all transverse. Figure 1.a. shows the image of a transverse wave, figure 1.b. shows the image of an electromagnetic wave. In special circumstances standing waves can be produced, this happens when a sound wave interferes with its own reflection. Sound waves superimpose to produce a steady state distribution of energy, standing waves don’t travel, instead a pattern forms with regions of zero oscillation (called nodes) and maximum oscillation (called anti-nodes) both are fixed in space. Figure 1.c. shows that these two waves have the same amplitude and frequency travelling in opposite directions, as they combine you can see a fixed pattern of nodes and anti-nodes. The electromagnetic spectrum is the range of electromagnetic waves, they vary in both frequency and wavelength. Radio waves have the longest wave length and lowest frequency, while Gamma rays have the shortest wavelength and highest frequency. Figure 1.d. shows an image of the electromagnetic spectrum. All electromagnetic waves are transverse and can all travel through a vacuum. They also require no medium. The sun produces all electromagnetic waves, they are produced by a vibrating electric charge, meaning that they consist of both an electric and magnetic component. All electromagnetic waves travel at the speed of light and in a straight line unless there is a change in the medium. If there is a change then the ... ... middle of paper ... ...h day. Each satellite transmissions radio waves to earth that hold information regarding its location and time. Anyone can obtain this information through GPS receivers, which identify and decipher the information from the satellites. The positioning information from GPS satellites is sent in the form of repeating codes which a GPS receiver can use to determine its position on the Earth (latitude and longitude) with an accuracy of approximately 10 m. There are more sophisticated receivers that can be used to determine position with precision of a few millimetres. The codes which form the GPS signal structure are superimposed upon two carrier waves. Both the carrier frequencies and the signal frequencies are resultant directly from the on-board atomic clock oscillator frequency of 10.23 MHz. figure 1.g. shows the image of the earth surround by the GPS satellites.

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