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In the case of electromagnetic radiation—such as light—in free space, the phase speed is the speed of light, about 3 × 10 8 m/s. Thus the wavelength of a 100 MHz electromagnetic (radio) wave is about: 3 × 10 8 m/s divided by 10 8 Hz = 3 m.
Lambda (written λ, in lowercase) is a non-SI unit of volume equal to 10 −9 m 3, 1 cubic millimetre (mm 3) or 1 microlitre (μL). Introduced by the BIPM in 1880, [ 1 ] the lambda has been used in chemistry [ 2 ] and in law for measuring volume, but its use is not recommended.
x, s, d, u, x 1, s 1, d 1, u 1: m [L] Image distance x', s', d', v, x 2, s 2, d 2, v 2: m [L] Object height y, h, y 1, h 1: m [L] Image height y', h', H, y 2, h 2, H 2: m [L] Angle subtended by object θ, θ o, θ 1: rad dimensionless Angle subtended by image θ', θ i, θ 2: rad dimensionless Curvature radius of lens/mirror r, R: m [L] Focal ...
How interference works. The distance between the bright fringe (a) and the dark fringe (b) indicates a change in the light path length of 1/2 the wavelength, so a change of the width of the gap of 1/4 wavelength. So the distance between two bright or dark fringes indicates a change in the gap of 1/2 wavelength.
Wavenumber has dimensions of reciprocal length, so its SI unit is the reciprocal of meters (m −1). In spectroscopy it is usual to give wavenumbers in cgs unit (i.e., reciprocal centimeters; cm −1 ); in this context, the wavenumber was formerly called the kayser , after Heinrich Kayser (some older scientific papers used this unit ...
Formally, the wavelength version of Wien's displacement law states that the spectral radiance of black-body radiation per unit wavelength, peaks at the wavelength given by: = where T is the absolute temperature and b is a constant of proportionality called Wien's displacement constant, equal to 2.897 771 955... × 10 −3 m⋅K, [1] [2] or b ...
Full width at half maximum. In a distribution, full width at half maximum (FWHM) is the difference between the two values of the independent variable at which the dependent variable is equal to half of its maximum value. In other words, it is the width of a spectrum curve measured between those points on the y-axis which are half the maximum ...
The equivalent width of a spectral line is a measure of the area of the line on a plot of intensity versus wavelength in relation to underlying continuum level. It is found by forming a rectangle with a height equal to that of continuum emission, and finding the width such that the area of the rectangle is equal to the area in the spectral line.