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Coercivity, also called the magnetic coercivity, coercive field or coercive force, is a measure of the ability of a ferromagnetic material to withstand an external magnetic field without becoming demagnetized. Coercivity is usually measured in oersted or ampere/meter units and is denoted H C.
The force on an electric charge depends on its location, speed, and direction; two vector fields are used to describe this force. [2]: ch1 The first is the electric field, which describes the force acting on a stationary charge and gives the component of the force that is independent of motion.
Thus, a piece of iron in its lowest energy state ("unmagnetized") generally has little or no net magnetic field. However, the magnetic domains in a material are not fixed in place; they are simply regions where the spins of the electrons have aligned spontaneously due to their magnetic fields, and thus can be altered by an external magnetic field.
Similarly, if only the magnetic field (B) is non-zero and is constant in time, the field is said to be a magnetostatic field. However, if either the electric or magnetic field has a time-dependence, then both fields must be considered together as a coupled electromagnetic field using Maxwell's equations. [9]
Lorentz force on a charged particle (of charge q) in motion (velocity v), used as the definition of the E field and B field. Here subscripts e and m are used to differ between electric and magnetic charges. The definitions for monopoles are of theoretical interest, although real magnetic dipoles can be described using pole strengths.
electric flux: volt metre: V⋅m kg⋅m 3 ⋅s −3 ⋅A −1: E electric field strength volt per metre: V/m = N/C kg⋅m⋅A −1 ⋅s −3: D electric displacement field: coulomb per square metre: C/m 2: A⋅s⋅m −2: ε permittivity: farad per metre: F/m kg −1 ⋅m −3 ⋅A 2 ⋅s 4: χ e electric susceptibility (dimensionless) 1 1 p ...
Similarly, if only the magnetic field (B) is non-zero and is constant in time, the field is said to be a magnetostatic field. However, if either the electric or magnetic field has a time-dependence, then both fields must be considered together as a coupled electromagnetic field using Maxwell's equations.
Magnetostriction applies to magnetic fields, while electrostriction applies to electric fields. Magnetostriction causes energy loss due to frictional heating in susceptible ferromagnetic cores, and is also responsible for the low-pitched humming sound that can be heard coming from transformers, where alternating currents produce a changing ...