the weber is the si unit for magnetic field strength.
the weber is the si unit for magnetic field strength.
what is the si unit for magnetic field strength?
the weber
an rf electromagnetic wave has both an electric and a magnetic component (electric field and magnetic field), and it is often convenient to express the intensity of the rf environment at a given location in terms of units specific to each component. for example, the unit "volts per meter" (v/m) is used to express the strength of the electric field (electric "field strength"), and the unit "amperes per meter" (a/m) is used to express the strength of the magnetic field (magnetic "field strength"). another commonly used unit for characterizing the total electromagnetic field is "power density." power density is most appropriately used when the point of measurement is far enough away from an antenna to be located in the "far-field" zone of the antenna.
high-intensity radiated field
since most of the magnetic field is confined within the outlines of the core loop, this allows a simplification of the mathematical analysis. see the drawing at right. a common simplifying assumption satisfied by many electromagnets, which will be used in this section, is that the magnetic field strength "b" is constant around the magnetic circuit (within the core and air gaps) and zero outside it. most of the magnetic field will be concentrated in the core material "(c)". within the core the magnetic field "(b)" will be approximately uniform across any cross section, so if in addition the core has roughly constant area throughout its length, the field in the core will be constant. this just leaves the air gaps "(g)", if any, between core sections. in the gaps the magnetic field lines are no longer confined by the core, so they 'bulge' out beyond the outlines of the core before curving back to enter the next piece of core material, reducing the field strength in the gap. the bulges "(b)" are called "fringing fields". however, as long as the length of the gap is smaller than the cross section dimensions of the core, the field in the gap will be approximately the same as in the core. in addition, some of the magnetic field lines "(b)" will take 'short cuts' and not pass through the entire core circuit, and thus will not contribute to the force exerted by the magnet. this also includes field lines that encircle the wire windings but do not enter the core. this is called "leakage flux". therefore, the equations in this section are valid for electromagnets for which:
electromagnet