Search results
Results from the WOW.Com Content Network
The Biot–Savart law [4]: Sec 5-2-1 is used for computing the resultant magnetic flux density B at position r in 3D-space generated by a filamentary current I (for example due to a wire). A steady (or stationary) current is a continual flow of charges which does not change with time and the charge neither accumulates nor depletes at any point.
One difference between the Gaussian and SI systems is in the factor 4π in various formulas that relate the quantities that they define. With SI electromagnetic units, called rationalized, [3] [4] Maxwell's equations have no explicit factors of 4π in the formulae, whereas the inverse-square force laws – Coulomb's law and the Biot–Savart law – do have a factor of 4π attached to the r 2.
Alternatively, introductory treatments of magnetism introduce the Biot–Savart law, which describes the magnetic field associated with an electric current. An observer at rest with respect to a system of static, free charges will see no magnetic field.
If all currents in a system are known (i.e., if a complete description of the current density () is available) then the magnetic field can be determined, at a position r, from the currents by the Biot–Savart equation: [3]: 174 = (′) (′) | ′ | ′
Magnetic scalar potential, ψ, is a quantity in classical electromagnetism analogous to electric potential.It is used to specify the magnetic H-field in cases when there are no free currents, in a manner analogous to using the electric potential to determine the electric field in electrostatics.
Position vectors r and r′ used in the calculation. The starting point is Maxwell's equations in the potential formulation using the Lorenz gauge: =, = where φ(r, t) is the electric potential and A(r, t) is the magnetic vector potential, for an arbitrary source of charge density ρ(r, t) and current density J(r, t), and is the D'Alembert operator. [2]
Biot–Savart law describes the magnetic field set up by a steady current density. Named for Jean-Baptiste Biot and Félix Savart . Birch's law , in geophysics , establishes a linear relation of the compressional wave velocity of rocks and minerals of a constant average atomic weight.
Magnetic vector potential was independently introduced by Franz Ernst Neumann [1] and Wilhelm Eduard Weber [2] in 1845 and in 1846, respectively to discuss Ampère's circuital law. [3] William Thomson also introduced the modern version of the vector potential in 1847, along with the formula relating it to the magnetic field.