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Magnetic reluctance, or magnetic resistance, is a concept used in the analysis of magnetic circuits. It is defined as the ratio of magnetomotive force (mmf) to magnetic flux . It represents the opposition to magnetic flux, and depends on the geometry and composition of an object.
The first magnetoresistive effect was discovered in 1856 by William Thomson, better known as Lord Kelvin, but he was unable to lower the electrical resistance of anything by more than 5%. Today, systems including semimetals [3] and concentric ring EMR structures are known. In these, a magnetic field can adjust the resistance by orders of magnitude.
Paramagnetic materials are attracted to magnetic fields, hence have a relative magnetic permeability greater than one (or, equivalently, a positive magnetic susceptibility). The magnetic moment induced by the applied field is linear in the field strength, and it is rather weak. It typically requires a sensitive analytical balance to detect the ...
The magnetic field (B, green lines) of one wire induces circular eddy currents (E) in the other wire. The eddy current flows in the opposite direction to the main current on the adjacent side of the wire (1) reducing it, but flows in the same direction as the main current on the far side of the wire (2) , increasing it.
The definitions for monopoles are of theoretical interest, although real magnetic dipoles can be described using pole strengths. There are two possible units for monopole strength, Wb (Weber) and A m (Ampere metre). Dimensional analysis shows that magnetic charges relate by q m (Wb) = μ 0 q m (Am).
Litz wire is used for the helix and variometer in both helix houses. It consists of 9 × 5 × 5 × 27 (totaling 6,075) strands of #36 AWG (0.127 mm [0.0050 in] diameter) magnet wire and multiple layers of cotton, hemp, and plastic insulation, in a cable 19 mm (3 ⁄ 4 inch) in diameter, totaling 151,875 circular mils (0.7695619839 cm 2) of ...
Magnetic field (green) induced by a current-carrying wire winding (red) in a magnetic circuit consisting of an iron core C forming a closed loop with two air gaps G in it. In an analogy to an electric circuit, the winding acts analogously to an electric battery, providing the magnetizing field , the core pieces act like wires, and the gaps G act like resistors.
In most cases this is a small portion of a wire's inductance which includes the effect of induction from magnetic fields outside of the wire produced by the current in the wire. Unlike that external inductance, the internal inductance is reduced by skin effect, that is, at frequencies where skin depth is no longer large compared to the ...