Search results
Results from the WOW.Com Content Network
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.
It equals the spatial frequency. 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.
This animation portrays the de Broglie phase and group velocities (in slow motion) of three free electrons traveling over a field 0.4 ångströms in width. The momentum per unit mass (proper velocity) of the middle electron is lightspeed, so that its group velocity is 0.707 c. The top electron has twice the momentum, while the bottom electron ...
A calculation using Airy discs as point spread function shows that at Dawes' limit there is a 5% dip between the two maxima, whereas at Rayleigh's criterion there is a 26.3% dip. [3] Modern image processing techniques including deconvolution of the point spread function allow resolution of binaries with even less angular separation.
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.
Visulization of flux through differential area and solid angle. As always ^ is the unit normal to the incident surface A, = ^, and ^ is a unit vector in the direction of incident flux on the area element, θ is the angle between them.
The ratio of this measured beam parameter product to that of the ideal is defined as M 2, so that M 2 =1 describes an ideal beam. The M 2 value of a beam is conserved when it is transformed by diffraction-limited optics. The outputs of many low and moderately powered lasers have M 2 values of 1.2 or less, and are essentially diffraction-limited.