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In frequency (and thus energy), UV rays sit between the violet end of the visible spectrum and the X-ray range. The UV wavelength spectrum ranges from 399 nm to 10 nm and is divided into 3 sections: UVA, UVB, and UVC. UV is the lowest energy range energetic enough to ionize atoms, separating electrons from them, and thus causing chemical reactions.
Photon energy is the energy carried by a single photon. The amount of energy is directly proportional to the photon's electromagnetic frequency and thus, equivalently, is inversely proportional to the wavelength. The higher the photon's frequency, the higher its energy. Equivalently, the longer the photon's wavelength, the lower its energy.
The term wavelength may also apply to the repeating envelope of modulated waves or waves formed by interference of several sinusoids. [ 5 ] Assuming a sinusoidal wave moving at a fixed wave speed, wavelength is inversely proportional to the frequency of the wave: waves with higher frequencies have shorter wavelengths, and lower frequencies have ...
A photon has an energy, E, proportional to its frequency, f, by = = where h is the Planck constant, is the wavelength and c is the speed of light. This is sometimes known as the Planck–Einstein equation. [31]
For example, a wavenumber in inverse centimeters can be converted to a frequency expressed in the unit gigahertz by multiplying by 29.979 2458 cm/ns (the speed of light, in centimeters per nanosecond); [5] conversely, an electromagnetic wave at 29.9792458 GHz has a wavelength of 1 cm in free space.
The more general description of matter waves corresponding to a single particle type (e.g. a single electron or neutron only) would have a form similar to = (,) (() /) where now there is an additional spatial term (,) in the front, and the energy has been written more generally as a function of the wave vector. The various terms given ...
In addition, the law may be expressed in other terms, such as the number of photons emitted at a certain wavelength, or the energy density in a volume of radiation. In the limit of low frequencies (i.e. long wavelengths), Planck's law tends to the Rayleigh–Jeans law , while in the limit of high frequencies (i.e. small wavelengths) it tends to ...
The Planck constant, or Planck's constant, denoted by , [1] is a fundamental physical constant [1] of foundational importance in quantum mechanics: a photon's energy is equal to its frequency multiplied by the Planck constant, and the wavelength of a matter wave equals the Planck constant divided by the associated particle momentum.