Electromagnetic radiation and B fields in EMR are in-phase (see math section below). An important aspect of light's nature is its frequency. The frequency of a wave is its rate of oscillation and is measured in hertz, the SI unit of frequency, where one hertz is equal to one oscillation per second. Light usually has multiple frequencies that sum to form the resultant wave. Different frequencies undergo different angles of refraction, a phenomenon known as dispersion. A wave consists of successive troughs and crests, and the distance between two adjacent crests or troughs is called the wavelength. Waves of the electromagnetic spectrum
Genetic distance and Reynolds, Weir and Cockerham's genetic distance, listed below. In all the formulae in this section, formula_1 and formula_2 represent two different populations for which formula_3 loci have been studied. Let formula_4 represent the formula_5 allele at the formula_6 locus. In 1972, Masatoshi Nei published what came to be known as Nei's standard genetic distance. This distance has the nice property that if the rate of genetic change (amino acid substitution) is constant per year or generation then Nei's standard genetic distance ("D") increases in proportion to divergence time. This measure assumes that genetic differences are caused by mutation and