Electromagnetic spectrum, the entire distribution of electromagnetic radiation according to frequency or wavelength. Although all electromagnetic waves travel at. Electromagnetic waves can be described by their wavelengths, energy, and frequency. All three of these things describe a different property of light, yet they are. The electromagnetic spectrum is the range of frequencies (the spectrum) of electromagnetic . Photon energy is directly proportional to the wave frequency, so gamma ray photons have These relations are illustrated by the following equations: Wavelengths of electromagnetic radiation, no matter what medium they are.
Magnetic and electric fields of an electromagnetic wave are perpendicular to each other and to the direction of the wave. A wavelength is the distance between two consecutive peaks of a wave. This distance is given in meters m or fractions thereof. Frequency is the number of waves that form in a given length of time. It is usually measured as the number of wave cycles per second, or hertz Hz.
Similarly, a longer wavelength has a lower frequency because each cycle takes longer to complete. The EM spectrum EM radiation spans an enormous range of wavelengths and frequencies. This range is known as the electromagnetic spectrum. The EM spectrum is generally divided into seven regions, in order of decreasing wavelength and increasing energy and frequency.
The common designations are: Typically, lower-energy radiation, such as radio waves, is expressed as frequency; microwaves, infrared, visible and UV light are usually expressed as wavelength; and higher-energy radiation, such as X-rays and gamma rays, is expressed in terms of energy per photon.
Electromagnetic spectrum - Wikipedia
The electromagnetic spectrum is generally divided into seven regions, in order of decreasing wavelength and increasing energy and frequency: Biro Emoke Shutterstock Radio waves Radio waves are at the lowest range of the EM spectrum, with frequencies of up to about 30 billion hertz, or 30 gigahertz GHzand wavelengths greater than about 10 millimeters 0.
Radio is used primarily for communications including voice, data and entertainment media. They have frequencies from about 3 GHz up to about 30 trillion hertz, or 30 terahertz THzand wavelengths of about 10 mm 0. Microwaves are used for high-bandwidth communications, radar and as a heat source for microwave ovens and industrial applications.
Infrared Infrared is in the range of the EM spectrum between microwaves and visible light. IR light is invisible to human eyes, but we can feel it as heat if the intensity is sufficient. It has frequencies of about THz to THz and wavelengths of about nm 0. More generally, visible light is defined as the wavelengths that are visible to most human eyes.
Ultraviolet Ultraviolet light is in the range of the EM spectrum between visible light and X-rays. UV light is a component of sunlight; however, it is invisible to the human eye. It has numerous medical and industrial applications, but it can damage living tissue. Microwaves are the main wavelengths used in radarand are used for satellite communicationand wireless networking technologies such as Wi-Fialthough this is at intensity levels unable to cause thermal heating.
The copper cables transmission lines which are used to carry lower frequency radio waves to antennas have excessive power losses at microwave frequencies, and metal pipes called waveguides are used to carry them. Although at the low end of the band the atmosphere is mainly transparent, at the upper end of the band absorption of microwaves by atmospheric gasses limits practical propagation distances to a few kilometers.
Terahertz radiation Main article: Terahertz radiation Terahertz radiation is a region of the spectrum between far infrared and microwaves. Until recently, the range was rarely studied and few sources existed for microwave energy at the high end of the band sub-millimeter waves or so-called terahertz wavesbut applications such as imaging and communications are now appearing. Scientists are also looking to apply terahertz technology in the armed forces, where high-frequency waves might be directed at enemy troops to incapacitate their electronic equipment.
Infrared radiation Main article: It can be divided into three parts: The lower part of this range may also be called microwaves or terahertz waves.
- Electromagnetic Spectrum - Wavelength, Frequency, And Energy, Wavelength Regions
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This radiation is typically absorbed by so-called rotational modes in gas-phase molecules, by molecular motions in liquids, and by phonons in solids. The water in Earth's atmosphere absorbs so strongly in this range that it renders the atmosphere in effect opaque. However, there are certain wavelength ranges "windows" within the opaque range that allow partial transmission, and can be used for astronomy.
What Is Electromagnetic Radiation?
Mid-infrared, from 30 to THz 10—2. Hot objects black-body radiators can radiate strongly in this range, and human skin at normal body temperature radiates strongly at the lower end of this region. This radiation is absorbed by molecular vibrations, where the different atoms in a molecule vibrate around their equilibrium positions.
This range is sometimes called the fingerprint region, since the mid-infrared absorption spectrum of a compound is very specific for that compound. Physical processes that are relevant for this range are similar to those for visible light. The highest frequencies in this region can be detected directly by some types of photographic film, and by many types of solid state image sensors for infrared photography and videography.Light: Crash Course Astronomy #24
Visible radiation light Main article: Visible spectrum Above infrared in frequency comes visible light. The Sun emits its peak power in the visible region, although integrating the entire emission power spectrum through all wavelengths shows that the Sun emits slightly more infrared than visible light. Visible light and near-infrared light is typically absorbed and emitted by electrons in molecules and atoms that move from one energy level to another. This action allows the chemical mechanisms that underlie human vision and plant photosynthesis.
The light that excites the human visual system is a very small portion of the electromagnetic spectrum. A rainbow shows the optical visible part of the electromagnetic spectrum; infrared if it could be seen would be located just beyond the red side of the rainbow with ultraviolet appearing just beyond the violet end.
White light is a combination of lights of different wavelengths in the visible spectrum. If radiation having a frequency in the visible region of the EM spectrum reflects off an object, say, a bowl of fruit, and then strikes the eyes, this results in visual perception of the scene.
The brain's visual system processes the multitude of reflected frequencies into different shades and hues, and through this insufficiently-understood psychophysical phenomenon, most people perceive a bowl of fruit. At most wavelengths, however, the information carried by electromagnetic radiation is not directly detected by human senses.
Natural sources produce EM radiation across the spectrum, and technology can also manipulate a broad range of wavelengths. Optical fiber transmits light that, although not necessarily in the visible part of the spectrum it is usually infraredcan carry information. The modulation is similar to that used with radio waves. Ultraviolet radiation Main article: The wavelength of UV rays is shorter than the violet end of the visible spectrum but longer than the X-ray.
UV is the longest wavelength radiation whose photons are energetic enough to ionize atoms, separating electrons from them, and thus causing chemical reactions. Short wavelength UV and the shorter wavelength radiation above it X-rays and gamma rays are called ionizing radiationand exposure to them can damage living tissue, making them a health hazard. UV can also cause many substances to glow with visible light; this is called fluorescence.