Infrared rays are employed in electronic devices such as remote controls, TVs, and burglar alarms. They are also found in optical fibers. Infrared waves are related to the infrared spectrum, which is part of the wavelength range from 795 nm to 124 nm. Waves in this range can be transmitted through air or other materials.
Unlike radio waves, which can be reflected back toward a source by any electrically conductive surface, infrared radiation is absorbed by all solid materials except certain minerals. This property allows infrared sensors to detect objects hidden behind other objects. Also, unlike radar systems that transmit signals that reflect off of objects, infrared systems transmit signals that are directly absorbed by objects (except for some special cases). This makes infrared detection possible even when objects are standing inside large buildings or other enclosed spaces where they would be blocked from view with a radar system.
In addition to seeing things that are hidden in darkness, cameras can also see through fog, dust, and smoke particles. Although the term "visual" sounds like something visible to the human eye, it is actually the ability to see using different parts of the electromagnetic spectrum. Cameras use lenses and other optics to focus images onto sensing devices called photodiodes.
Waves of infrared light To change channels on your television, a remote control uses light waves that are just beyond the visible spectrum of light—infrared light waves. This spectrum is divided into three parts: near-infrared, mid-infrared, and far-infrared. Near-infrared waves are like those found in sunlight, but with the color removed. They're used to send signals through objects such as walls and windows that contain no glass. Mid-range wavelengths are similar to mid-range tones on a piano. They're used to produce colors on TV screens and other devices. Far-infrared rays are like X-rays, but they can't pass through ordinary matter. They're used by thermal imaging cameras, which record the difference between the heat given off by humans and animals and other hot objects, and the background temperature of the air, soil, and other things around them.
Near-infrared waves are invisible to the human eye but are received by special sensors located inside many modern appliances, including TVs. These sensors respond only to this type of waveform, so an appliance will need one sensor for the remote control signal and another for the microphone signal. Mid-range waves are visible to the naked eye, but they're used by radio frequency (RF) remotes to transmit information without touching. These waves are blocked by the human body, so they aren't useful for remote controls.
Electromagnetic waves are employed in the construction of different military safety equipment, such as night-vision goggles, cameras, and so on. The lens of the camera and the goggles are coated with a limited band of infrared radiation. This allows these devices to function even in darkness.
Military applications of electromagnetic waves include radio frequency (RF) weapons, radar systems, and communication electronics. RF weapons use electro-magnetic energy in the form of waves or beams for attacking enemies at a distance by causing damage to their electronic components. For example, an RF weapon can be used to destroy vehicles by sending out a high-powered signal that causes any metal parts within range of the beam to heat up until they burn away.
Radar is very important for the operation of military equipment and personnel. Radar detects aircraft, missiles, and other radar-sensitive objects using radio waves. Modern radar uses microwaves, but early radars used radio waves instead. Microwave radar works by transmitting a continuous wave into the air, which is then reflected back by any object in its path. The return signal contains information about the nature of the object, such as its size, speed, and direction. Military applications include target detection and location, aerial combat, and missile guidance.
This set's terms (6)
Electromagnetic wave behavior and application
Radio waves are a form of electromagnetic radiation that is most recognized for their application in communication technologies such as television, mobile phones, and radios. These devices pick up radio signals and turn them into mechanical vibrations in the speaker, which produces sound waves. The electromagnetic waves are generated by an electric current flowing through a conductor such as a copper wire or antenna.
Light is also an electromagnetic wave. It has two forms: visible light and infrared light. Visible light has frequencies between 400 and 700 nanometers (nm). Infrared light has frequencies between 0.7 and 1000 microns (μm). Electricity flows along the conductor (wire) to produce the magnetic field, and the oscillating electrons in the conductor radiate energy out into space. It should be noted that this process can only happen if there is free space around the conductor where it can oscillate; otherwise, it would just travel in a straight line like an electrical signal.
Communication using light was first demonstrated in 1835 by British scientist Michael Faraday. He isolated an electric circuit from its battery source and showed that it could function without being recharged. This led him to conjecture that the flow of electricity through a conductor such as a copper wire might cause another current to flow in the opposite direction, thereby transmitting information over long distances without any other connection than the one between the caller and the receiver.