Search results
Results From The WOW.Com Content Network
Magnetic induction B (also known as magnetic flux density) has the SI unit tesla [T or Wb/m 2]. [1] One tesla is equal to 10 4 gauss. Magnetic field drops off as the inverse cube of the distance ( 1 / distance 3 ) from a dipole source. Energy required to produce laboratory magnetic fields increases with the square of magnetic field. [2]
1 T to 2.4 T – coil gap of a typical loudspeaker magnet; 1.5 T to 3 T – strength of medical magnetic resonance imaging systems in practice, experimentally up to 17 T [10] 4 T – strength of the superconducting magnet built around the CMS detector at CERN [11] 5.16 T – the strength of a specially designed room temperature Halbach array [12]
Continuous charge distribution. The volume charge density ρ is the amount of charge per unit volume (cube), surface charge density σ is amount per unit surface area (circle) with outward unit normal n̂, d is the dipole moment between two point charges, the volume density of these is the polarization density P.
Gauss's law for magnetism and the Faraday–Maxwell law can be grouped together since the equations are homogeneous, and be seen as geometric identities expressing the field F (a 2-form), which can be derived from the 4-potential A. Gauss's law for electricity and the Ampere–Maxwell law could be seen as the dynamical equations of motion of ...
The gauss is the unit of magnetic flux density B in the system of Gaussian units and is equal to Mx/cm 2 or g/Bi/s 2, while the oersted is the unit of H-field. One tesla (T) corresponds to 10 4 gauss, and one ampere (A) per metre corresponds to 4π × 10 −3 oersted .
The formula provides a natural generalization of the Coulomb's law for cases where the source charge is moving: = [′ ′ + ′ (′ ′) + ′] = ′ Here, and are the electric and magnetic fields respectively, is the electric charge, is the vacuum permittivity (electric field constant) and is the speed of light.
When the integrals above are evaluated for typical cases, e.g. of an oscillating current (or charge), they are found to give both a magnetic field component varying according to r −2 (the induction field) and a component decreasing as r −1 (the radiation field). [clarification needed]
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.