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The rms charge radius is a measure of the size of an atomic nucleus, particularly the proton distribution. The proton radius is about one femtometre = 10−15 metre. It can be measured by the scattering of electrons by the nucleus. Relative changes in the mean squared nuclear charge distribution can be precisely measured with atomic spectroscopy .
Ten-codes, especially "10-4" (meaning "understood") first reached public recognition in the mid- to late-1950s through the popular television series Highway Patrol, with Broderick Crawford. [ citation needed ] Crawford would reach into his patrol car to use the microphone to answer a call and precede his response with "10-4".
Negative refraction. Negative refraction is the electromagnetic phenomenon where light rays become refracted at an interface that is opposite to their more commonly observed positive refractive properties. Negative refraction can be obtained by using a metamaterial which has been designed to achieve a negative value for (electric) permittivity ...
Moseley's law. Moseley's law is an empirical law concerning the characteristic X-rays emitted by atoms. The law had been discovered and published by the English physicist Henry Moseley in 1913–1914. [1] [2] Until Moseley's work, "atomic number" was merely an element's place in the periodic table and was not known to be associated with any ...
The mass-to-charge ratio ( m / Q) is a physical quantity relating the mass (quantity of matter) and the electric charge of a given particle, expressed in units of kilograms per coulomb (kg/C). It is most widely used in the electrodynamics of charged particles, e.g. in electron optics and ion optics .
The small-angle approximations can be used to approximate the values of the main trigonometric functions, provided that the angle in question is small and is measured in radians : These approximations have a wide range of uses in branches of physics and engineering, including mechanics, electromagnetism, optics, cartography, astronomy, and ...
Electromagnetism. In special and general relativity, the four-current (technically the four-current density) [1] is the four-dimensional analogue of the current density, with units of charge per unit time per unit area. Also known as vector current, it is used in the geometric context of four-dimensional spacetime, rather than separating time ...
In Rutherford's notation, e is the elementary charge, N is the charge number of the nucleus (we now know this to be equal to the atomic number), and E is the charge of an alpha particle. The convention in Rutherford's time was to measure charge in electrostatic units , distance in centimeters, force in dynes , and energy in ergs .