Magnetometer
Magnetic fields are vector quantities characterized by both strength and direction. The strength of a magnetic field is measured in units of tesla in the SI units, and in gauss in the cgs system of units. 10,000 gauss are equal to one tesla. Measurements of the Earth's magnetic field are often quoted in units of nanotesla (nT), also called a gamma. The Earth's magnetic field can vary from 20,000 to 80,000 nT depending on location, fluctuations in the Earth's magnetic field are on the order of 100 nT, and magnetic field variations due to magnetic anomalies can be in the picotesla (pT) range. "Gaussmeters" and "teslameters" are magnetometers that measure in units of gauss or tesla, respectively. In some contexts, magnetometer is the term used for an instrument that measures fields of less than 1 millitesla (mT) and gaussmeter is used for those measuring greater than 1 mT.
Electron scattering
The Lorentz force, named after Dutch physicist Hendrik Lorentz, for a charged particle "q" is given (in SI units) by the equation:
where "qE describes the electric force due to a present electric field,E", acting on "q".
And "qv x B describes the magnetic force due to a present magnetic field, B, acting on "q" when "q" is moving with velocity v".
Which can also be written as:
where formula_3 is the electric potential, and A is the magnetic vector potential.