MAGNET
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| Expression | SI-Unit | CGS-Unit | Conversion |
|---|---|---|---|
| Flux Density B | Tesla T = Vs/m2 | Gauss G | 1 T = 104 G |
| Field Strength H | A/m | Oersted Oe | 1 A/m = 0.012566 Oe |
| Magnetization M | A/m | Oersted Oe | 1 A/m = 0.012566 Oe |
| Polarization J | Tesla T = Vs/m2 | Gauss G | 1 T = 10⁴ G |
| Magnetic Moment m | Vsm | emu = G ㎤ | 1 Vsm = 1010 emu |
| Magnetic Flux F | Weber = Vs | Maxwell = G ㎠ | 1 Weber = 108 Maxwell |
| Energy Density (BH) | J/㎥ | GOe | 1 J/m3 = 125.66 GOe 1 kJ/m3 = 0.12566 MGOe |
| Permeabiliy m | Vs / Am | G/Oe | 1 Vs/Am = 7.958 105 G/Oe |
| Magnetic Potential Q | A | Gilbert = Oe cm | 1 A = 1.2566 Oe cm |
| SI → CGS | CGS → SI | |||
|---|---|---|---|---|
| Br | 1 (T) | 10,000 (G) | 1 (G) | 0.0001 (T) |
| H | 1 (A/m) | 0.01256 =1/80 (Oe) | 1 (Oe) | 79.577 = 80 (A/m) |
| (BH)max | 1 (J/㎥) | 125.664 =1000/8 (Goe) | 1 (GOe) | 0.00795 (J/㎥) |
| 1 (kJ/㎥) | 0.12566 = 1/8 (MGOe) | 1 (MGOe) | 7.9577 = 8 (kJ/㎥) | |
| Air Gap | Space between the poles of a magnet in which there exists a useable magnetic field. |
|---|---|
| Anisotropy | Directional dependence of a physical quantity : in the case of permanent magnets this relates to remanence, coercivity etc. |
| B (H) Curve | A curve representing the relationship between induction B and field strength H. |
| (BㆍH) | Product of the respective induction B and field strength H within a magnet. |
| (BㆍH)max - Value | Maximum product resulting from B and H on the demagnetization curve, i.e, the largest rectangle which can be drawn within the B (H) curve in the second quadrant of the hysteresis curve. this usually corresponds to the optimal working point. |
| Coercive Field Strength Hc, Coercivity | Strength of the demagnetizing field where B = 0 (HCB) or J = 0 (HcJ). |
| Curie Temperature | The temperature above which the remanence of polarization in a ferro-magnetic material becomes Jr = 0. At all temperatures above the Curie temperature all ferromagnetic materials are paramagnetic. |
| Demagnetization | Reduction of induction to B = 0; this is obtained practically by the application of an alternating field of decreasing amplitude. |
| Demagnetization Curve | The second quadrant of the hysteresis loop which is of great importance for permanent magnets. |
| Demagnetization Factor N | Shape dependent factor which determines the angle between working line and B-axis, N is the tangent of this angle. |
| Diamagnetism | Magnetic property of materials whose permeability m is smaller than 1, e.g. bismuth. |
| Effective Flux | Part of the magnetic flux which passes through the air gap. |
| Energy Density | 1/2 B H = half of the product resulting from the magnetic induction B and the field strength H(half of the rectangle within the demagnetization curve with its corner at the working point). |
| Ferromagnetism | Magnetic property of materials with a permeability m >> 1, e.g. iron, nickel, cobalt and many of their alloys and compounds. |
| Field | space having physical properties (see also magnetic field). |
| Field Strength (magnetic) H | a quantitative representation of the strength and the direction (vector) of a magnetic field. Unit 1 A/m = 0,01 A/cm = 0,01256 Oersted. |
| Flux Density B | No. of field lines per unit of surface. |
| Unit | 1 Tesla = 1 Vs/m2 = 10-4 Vs/cm2 = 104 Gauss. |
| Unit | 1 Weber (Wb) = 1 Vs = 108 Maxwell. |
| Fluxmeter | Electronic integrator for measuring a magnetic flux or induction. |
| Hall probe | Semiconductor probe for measuring magnetic fields, Hall-probes always are used connected to a gaußmeter. |
| Hard Ferrite | Term used in DIN 17410 for Oxide magnet materials. |
| Hybrid-material | Plastic bonded material containing several kinds of magnetic powders to adjust certain magnetic properties by using for example Neofer and oxide-powders to reach a predicted price. |
| Hysteresis - loop | Representation of induction B resp. Polarization J in relation to the magnetizing field strength H. |
| Induction | 1. The ability of the magnetic field to surround itself with an electric field whilst it is changing. 2. The term induction is also used to mean flux density B. |
| Isotropy | Equality of physical properties in all directions. |
| Magnetic | Commonly used to denote all materials with noticeably high permeability (especially iron, nickel, cobalt and their alloys); all other materials (gold, brass, copper, wood, stone, etc.) are considered to be non-magnetic. |
| Magnetic Circuit | Total of parts and gaps through which a magnetic flux passes in the case of a permanent magnet this consists of the magnet itself, the pole shoes, the air gap and the stray field. |
| Magnetic Field | Space in which mechanical forces have an effect on magnetic charges or where induction occurs. |
| Magnetization | 1) The noun arising from "magnetizing" 2) Polarization divided by the magnetic field constant M = J/mo, B = mo (H+M) = mO H + J. |
| Magnetizing | Process of aligning the molecular magnets by an external magnetic field. |
| Maxwell | Former unit of magnetic flux(1 Maxwell = 10-8 Wb = 10-8 Vs). |
| Oersted | Former unit of magnetic field strength 1 Oersted = 79,6 A/m = 0,796 A/cm = 0,0796kA/m. |
| Oerstedmeter | Instrument for measuring the magnetic field strength H (also known as Gaußmeter). |
| Oxide Magnet | Hard ferrite, ceramic magnet material, e.g. composed of iron oxide and barium oxide (Ba0 x 6 Fe203). |
| Permeance | Ratio of magnetic flux to magnetic potential difference in the case of an air gap surface : length). |
| Plastic bonded magnet material | If a magnet powder is blended with plastic material it is possible to apply methods of plastic industry (injection moulding, rolling etc.) to produce magnets of very complex shapes. The advantages : cheap manufacturing processes, small tolerances and many kinds shapes must be compared with the disadvantages : expensive tools and lower magnetic properties. |
| Potential, magnetic | Physical quantity of which the gradient gives the magnetic field H. Only a potential difference can be measured (magnetic tension between two points) as an integral of the field strength over any path between these two points, provided this path does not enclose an current-carrying conductor. |
| Rare earth magnet materials | The rare earth metals Nd and Sm are applied to different alloys for manufacturing permanent magnets with very high magnetic properties. The nowadays commercially exploited materials Seco and Neofer are based on the compositions SmCo5, Sm2(FeCo)17 and Nd2Fe14B. |
| Radial magnetization | Magnetizing a ring magnet between two coils carrying currents of opposite directions leads to a radial magnetization. One pole is on the inner circumference of the magnet the other pole on the outer circumference. |
| Saturation Polarization | Highest practically achievable magnetic polarization of a material when exposed to a sufficient strong magnetic field. |
| Sl-units | Physical units according to the System International (SI) which is based on the units kilogram, meter second and ampere. All other units are a product, a quotient or a power of these four basic units The traditional cgs-units resp. the Gauß-units in magnetism are still in use but have to be adapted by law. The following table shows some magnetic units and their conversion. |
| Material | (BH)max | Hcj | Max, Opreating. Temp |
|---|---|---|---|
| Flexible Ceramic |
Up to 2 MGOe | Up to 3 KOe | 100℃ |
| Hard Ceramic |
Up to 5 MGOe | Up to 5 KOe | 280℃ |
| AlNiCo | Up to 10 MGOe | Up to 2 KOe | 550℃ |
| NdFeB (Bonded) |
Up to 12 MGOe | Up to 16 KOe | 125℃ |
| NdFeB( Sintered) |
Up to 54 MGOe | Up to 40 KOe | 180℃ |
| Sm-Co (Sintered) |
Up to 35 MGOe | Up to 35 KOe | 250℃ |