WavesWaves 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 the medium. Waves can be classified as mechanical or electromagnetic. Mechanical waves require a medium and can be transverse or longitudinal. Electromagnetic waves do not require a medium and are all transversal. Figure 1.a. shows the image of a transverse wave, figure 1.b. shows an image of an electromagnetic wave. In particular circumstances standing waves can be produced, this happens when a sound wave interferes with its own reflection. Sound waves overlap to produce a steady-state energy distribution, standing waves do not travel, instead a pattern is formed with regions of zero oscillation (called nodes) and maximum oscillation (called anti-nodes), both fixed in space. Figure 1. C. shows that these two waves have the same amplitude and frequency traveling 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 wavelength 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 travel in a vacuum. They also do not require any means. The sun produces all electromagnetic waves, they are produced by a vibrating electric charge, which means they are made up of both an electric and a 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 transmits radio waves to the earth that contain information about its location and time. Anyone can obtain this information via GPS receivers, which identify and decipher information from satellites. Positioning information from GPS satellites is sent in the form of repetitive codes that a GPS receiver can use to determine its position on Earth (latitude and longitude) to an accuracy of about 10 m. There are more sophisticated receivers that can be used to determine the position with an accuracy of a few millimeters. The codes that form the structure of the GPS signal are superimposed on two carrier waves. Both carrier frequencies and signal frequencies result directly from the integrated atomic clock oscillator frequency of 10.23 MHz. figure 1.g. shows the image of the earth surrounded by GPS satellites.