Speed, Frequency and Wavelength - How they are related, with examples
How to render the color spectrum / Code – Only approximately right. Poster " Electromagnetic Radiation Spectrum" ( kB). Electromagnetic spectrum, the entire distribution of electromagnetic radiation according to frequency or wavelength. Although all electromagnetic waves travel at. Each color of light we see has a particular frequency - Here, the key relationship is i.e. part of the electromagnetic spectrum, and so travel at the speed of light.
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.
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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.
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. 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.
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.
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- Electromagnetic Spectrum - Wavelength, Frequency, And Energy, Wavelength Regions
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.
At the middle range of UV, UV rays cannot ionize but can break chemical bonds, making molecules unusually reactive. Sunburnfor example, is caused by the disruptive effects of middle range UV radiation on skin cellswhich is the main cause of skin cancer. UV rays in the middle range can irreparably damage the complex DNA molecules in the cells producing thymine dimers making it a very potent mutagen.
Providing we know any two of the three quantities we can find the other one, either directly or by rearranging the equation. The next section solves the equation as it is, and there is a calculator for frequency, wavelength and speed here.
Solving the Equation In this example we will consider the frequency of radio waves. Radio waves are just another form of "light", i.
Let's say we have a radio with a dial that is only marked in MHz. This is a measurement of frequency and we note that 1 MHz is the same as 1 million hertz the M in MHz stands for " mega ", which means million. We are told of a radio broadcast we want to hear but we are only given the wavelength of the station and not the frequency. The wavelength we are given is 3.
We know the speed of light and we know the wavelength so it's now an easy matter to plug these numbers into the equation and find the frequency of the radio station: This gives us a frequency of 92 MHz, which is found in the FM range of most domestic radios.
Light: Electromagnetic waves, the electromagnetic spectrum and photons
Visible Light The wavelengths of visible light are measured in nanometres, nm billionths of a metre but the equation works just the same. When we look at a light source the colours we see are dictated by the frequency of the light. These frequencies are very high by everyday standards. Have a look around the room and find something that's the colour red. How many times are the tiny crests of the light waves coming from that red object passing through the front of your eyes every second?
In other words, what is the frequency of red light?