The wave can also be absorbed by the material, indicating that there is some interaction between the wave and the material, such as the thermal agitation of molecules. If the material is opaque to the frequency, then the wave can be totally reflected. What happens when an electromagnetic wave impinges on a material? If the material is transparent to the particular frequency, then the wave can largely be transmitted. Note that there are exceptions to these rules of thumb. The shorter the wavelength of any electromagnetic wave probing a material, the smaller the detail it is possible to resolve.High-frequency electromagnetic waves can carry more information per unit time than low-frequency waves.High-frequency electromagnetic waves are more energetic and are more able to penetrate than low-frequency waves.Three rules that apply to electromagnetic waves in general are as follows: Many of the characteristics of the various types of electromagnetic waves are related to their frequencies and wavelengths, as we shall see. Thus, for all electromagnetic waves, the greater the frequency, the smaller the wavelength.įigure 1 shows how the various types of electromagnetic waves are categorized according to their wavelengths and frequencies-that is, it shows the electromagnetic spectrum. Here v W = c, so that for all electromagnetic waves, c = fλ. The relationship among these wave characteristics can be described by v W = fλ, where v W is the propagation speed of the wave, f is the frequency, and λ is the wavelength. This module concentrates on EM waves, but other modules contain examples of all of these characteristics for sound waves and submicroscopic particles.Īs noted before, an electromagnetic wave has a frequency and a wavelength associated with it and travels at the speed of light, or c. These are always related by the expression v W= fλ. Among the many shared attributes of waves are propagation speed, frequency, and wavelength. There are many types of waves, such as water waves and even earthquakes. Inner electronic transitions and fast collisions Thermal agitations & electronic transitions A brief overview of the production and utilization of electromagnetic waves is found in Table 1. We will also find that there are many connections with previously discussed topics, such as wavelength and resonance. In this module we examine how electromagnetic waves are classified into categories such as radio, infrared, ultraviolet, and so on, so that we can understand some of their similarities as well as some of their differences. List and explain the different methods by which electromagnetic waves are produced across the spectrum.Draw a simplified electromagnetic spectrum, indicating the relative positions, frequencies, and spacing of the different types of radiation bands.Explain why the higher the frequency, the shorter the wavelength of an electromagnetic wave.List three “rules of thumb” that apply to the different frequencies along the electromagnetic spectrum.Killing cancer cells, sterilising medical equipment, killing bacteria to prolong shelf life of fruit.By the end of this section, you will be able to: Medical images of bones, airport baggage scanners. Suntan, detecting forged bank notes, helps to make vitamin D, hardening some types of dental filling, nightclubs and bowling alleys to make clothes glow. Seeing, photography, optical fibre communication.

Heat transfer by radiation – electric heaters, cooking by grilling, also night vision equipment, optical fibre communication, TV remote control, burglar alarms. Communication such as television and radio, mobile phones, radar, Wi-Fi, Bluetooth.Ĭooking, satellite communication, speed cameras.

Electromagnetic spectrum