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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.
Transfer of momentum per unit time newton (N = kg⋅m⋅s −2) L M T −2: extensive, vector Frequency: f: Number of (periodic) occurrences per unit time hertz (Hz = s −1) T −1: scalar Half-life: t 1/2: Time for a quantity to decay to half its initial value s T: Heat: Q: Thermal energy: joule (J) L 2 M T −2: Heat capacity: C p: Energy ...
Irradiance of a surface per unit frequency or wavelength. This is sometimes also confusingly called "spectral intensity". This is sometimes also confusingly called "spectral intensity". Non-SI units of spectral flux density include jansky ( 1 Jy = 10 −26 W⋅m −2 ⋅Hz −1 ) and solar flux unit ( 1 sfu = 10 −22 W⋅m −2 ⋅Hz −1 = 10 ...
The power spectral density (PSD) of the signal describes the power present in the signal as a function of frequency, per unit frequency. Power spectral density is commonly expressed in SI units of watts per hertz (abbreviated as W/Hz). [2]
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 rate at which EM energy is detected by the detector is measured. This measured rate is then divided by Δλ to obtain the detected power per square metre per unit wavelength range. Spectral flux density is often used as the quantity on the y-axis of a graph representing the spectrum of a light-source, such as a star.
A flow chart describing the relationship of various physical quantities, including radiant flux and exitance. In radiometry, radiant flux or radiant power is the radiant energy emitted, reflected, transmitted, or received per unit time, and spectral flux or spectral power is the radiant flux per unit frequency or wavelength, depending on whether the spectrum is taken as a function of frequency ...
The 41.8% point is the wavelength-frequency-neutral peak (i.e. the peak in power per unit change in logarithm of wavelength or frequency). These are the points at which the respective Planck-law functions 1 / λ 5 , ν 3 and ν 2 / λ 2 , respectively, divided by exp ( hν / k B T ) − 1 attain their maxima.