Wave amplitude formula_4 described by the equation: where The units of the amplitude depend on the type of wave. Transverse mechanical waves (e.g., a wave on a string) have an amplitude expressed as a distance (e.g., meters), longitudinal mechanical waves (e.g., sound waves) use units of pressure (e.g., pascals), and electromagnetic waves (a form of transverse vacuum wave) express the amplitude in terms of its electric field (e.g., volts/meter). The wavelength formula_30 is the distance between two sequential crests or troughs (or other equivalent points), generally is measured in meters. A wavenumber formula_17, the spatial frequency of the wave in radians
Distance from a point to a plane the point on a plane formula_33 closest to an arbitrary point formula_34 is formula_2 given by where and the distance from the point to the plane is Distance from a point to a plane In Euclidean space, the point on a plane formula_1 that is closest to the origin has the Cartesian coordinates formula_2, where The distance between the origin and point formula_2 is formula_5. If what is desired is the distance from a point not at the origin to the nearest point on a plane, this can be found by a change of variables that moves the origin to