Flux surface surrounding a charge "q" is "q"/ε. In free space the electric displacement is given by the constitutive relation D = ε E, so for any bounding surface the D-field flux equals the charge "Q" within it. Here the expression "flux of" indicates a mathematical operation and, as can be seen, the result is not necessarily a "flow", since nothing actually flows along electric field lines. The magnetic flux density (magnetic field) having the unit Wb/m (Tesla) is denoted by B, and magnetic flux is defined analogously: with the same notation above. The quantity arises in Faraday's law of induction,
Maxwell (unit) Maxwell (unit) The maxwell (symbol: Mx) is the CGS (centimetre-gram-second) unit of magnetic flux (). The unit name honours James Clerk Maxwell, who presented a unified theory of electromagnetism. The "maxwell" was recommended as a CGS unit at the International Electrical Congress held in 1900 at Paris. This practical unit was previously called a "line", reflecting Faraday's conception of the magnetic field as curved lines of magnetic force, which he designated as "line of magnetic induction". "Kiloline" (10 line) and "megaline" (10 line) were sometimes used because 1 line was very small relative to the phenomena that it was used