磁學(xué)量常用單位換算

磁學(xué)量常用單位換算磁學(xué)量名稱SI符號和單位CGS符號和單位單位換算 磁通量韋伯(Wb)麥克斯韋（Mx）1Mx=10-8Wb 磁感應(yīng)強(qiáng)度B特斯拉(T )B高斯(Gs)1Gs=10-4T 磁場強(qiáng)度H安/米(A/m)H奧斯特(Oe)1Oe=103/4pA/m 磁化強(qiáng)度M安/米(A/m)M高斯（Gs）1Gs=103A/m 磁極化強(qiáng)度J特斯拉(T )4pM高斯（Gs）1Gs=10-4T 磁能積BH焦/米3(J/m3)BH高奧（GOe）1MGOe=102/4pkJ/m3 真空磁導(dǎo)率4p10-7H/m1磁概念永磁材料：永磁材料被外加磁場磁化后磁性不消失，可對外部空間提供穩(wěn)定磁場。釹鐵硼永磁體常用的衡量指標(biāo)有以下四種：剩磁（Br）單位為特斯拉（T）和高斯（Gs）1Gs =0.0001T將一個磁體在閉路環(huán)境下被外磁場充磁到技術(shù)飽和后撤消外磁場，此時磁體表現(xiàn)的磁感應(yīng)強(qiáng)度我們稱之為剩磁。它表示磁體所能提供的最大的磁通值。從退磁曲線上可見，它對應(yīng)于氣隙為零時的情況，故在實(shí)際磁路中磁體的磁感應(yīng)強(qiáng)度都小于剩磁。釹鐵硼是現(xiàn)今發(fā)現(xiàn)的Br最高的實(shí)用永磁材料。磁感矯頑力（Hcb）單位是安/米（A/m）和奧斯特（Oe）或1 Oe79.6A/m處于技術(shù)飽和磁化后的磁體在被反向充磁時，使磁感應(yīng)強(qiáng)度降為零所需反向磁場強(qiáng)度的值稱之為磁感矯頑力（Hcb）。但此時磁體的磁化強(qiáng)度并不為零，只是所加的反向磁場與磁體的磁化強(qiáng)度作用相互抵消。（對外磁感應(yīng)強(qiáng)度表現(xiàn)為零）此時若撤消外磁場，磁體仍具有一定的磁性能。釹鐵硼的矯頑力一般是11000Oe以上。內(nèi)稟矯頑力（Hcj）單位是安/米（A/m）和奧斯特（Oe）1 Oe79.6A/m使磁體的磁化強(qiáng)度降為零所需施加的反向磁場強(qiáng)度，我們稱之為內(nèi)稟矯頑力。內(nèi)稟矯頑力是衡量磁體抗退磁能力的一個物理量，如果外加的磁場等于磁體的內(nèi)稟矯頑力，磁體的磁性將會基本消除。釹鐵硼的Hcj會隨著溫度的升高而降低所以需要工作在高溫環(huán)境下時應(yīng)該選擇高Hcj的牌號。磁能積(BH)單位為焦/米3（J/m3）或高奧（GOe）1 MGOe7. 96k J/m3退磁曲線上任何一點(diǎn)的B和H的乘積既BH我們稱為磁能積,而BH的最大值稱之為最大磁能積(BH)max。磁能積是恒量磁體所儲存能量大小的重要參數(shù)之一，(BH)max越大說明磁體蘊(yùn)含的磁能量越大。設(shè)計(jì)磁路時要盡可能使磁體的工作點(diǎn)處在最大磁能積所對應(yīng)的B和H附近。各向同性磁體：任何方向磁性能都相同的磁體。各向異性磁體：不同方向上磁性能會有不同；且存在一個方向，在該方向取向時所得磁性能最高的磁體。燒結(jié)釹鐵硼永磁體是各向異性磁體。取向方向：各向異性的磁體能獲得最佳磁性能的方向稱為磁體的取向方向。也稱作“取向軸”，“易磁化軸”。磁場強(qiáng)度：指空間某處磁場的大小，用H表示，它的單位是安/米（A/m）。磁化強(qiáng)度：指材料內(nèi)部單位體積的磁矩矢量和，用M表示，單位是安/米（A/m）。磁感應(yīng)強(qiáng)度：磁感應(yīng)強(qiáng)度B的定義是：B=0(H+M)，其中H和M分別是磁化強(qiáng)度和磁場強(qiáng)度，而0是真空導(dǎo)磁率。磁感應(yīng)強(qiáng)度又稱為磁通密度，即單位面積內(nèi)的磁通量。單位是特斯拉（T）。磁通：給定面積內(nèi)的總磁感應(yīng)強(qiáng)度。當(dāng)磁感應(yīng)強(qiáng)度B均勻分布于磁體表面A時，磁通的一般算式為 =BA。磁通的SI單位是麥克斯韋。相對磁導(dǎo)率：媒介磁導(dǎo)率相對于真空磁導(dǎo)率的比值，即r= /o。在CGS單位制中，o=1。另外，空氣的相對磁導(dǎo)率在實(shí)際使用中往往值取為1，另外銅、鋁和不銹鋼材料的相對磁導(dǎo)率也近似為1。磁導(dǎo)：磁通與磁動勢F的比值，類似于電路中的電導(dǎo)。是反映材料導(dǎo)磁能力的一個物理量。磁導(dǎo)系數(shù)Pc：又為退磁系數(shù)，在退磁曲線上，磁感應(yīng)強(qiáng)度Bd與磁場強(qiáng)度Hd的比率，即Pc =Bd/Hd，磁導(dǎo)系數(shù)可用來估計(jì)各種條件下的磁通值。對于孤立磁體Pc只與磁體的尺寸有關(guān)，退磁曲線和Pc線的交點(diǎn)就是磁體的工作點(diǎn)，Pc越大磁體工作點(diǎn)越高，越不容易被退磁。一般情況下對于一個孤立磁體取向長度相對越大Pc越大。因此Pc是永磁磁路設(shè)計(jì)中的一個重要的物理量。Glossary of Magnet TerminologyAir Gap -The external distance from one pole of the magnet to the other though a non-magnetic material (usually air).Anisotropic -An anisotropic material has different properties in different directions. For example, wood which has a grain is stronger in some one direction than another. Like wood, neodymium magnets are also anisotropic. Even before it is magnetized, a neodymium magnet has a preferred magnetization direction. See our articleAll About Magnetization Directionfor more info.Neodymium magnets are made with a preferred magnetization direction which can not be changed. These materials are either manufactured in the influence of strong magnetic fields or pressed a specific way, and can only be magnetized through the preferred axis.Sintered Neodymium (Iron Boron) and Samarium Cobalt magnets are anisotropic.B/H Curve -The result of plotting the value of the magnetic field (H) that is applied against the resultant flux density (B) achieved. This curve describes the qualities of any magnetic material. A graphic explanation can be foundhere.BHmax(Maximum Energy Product)-The Maximum Energy Product at the point on the B/H Curve that has the most strength, expressed in MGOe (MegaGaussOersteds). When describing the grade of a neodymium magnet, this number is commonly referred to as the N number, as in Grade N52 magnets.In the picture at right, it is the area inside the box, under the curve.Brmax(Residual Induction)-Also called Residual Flux Density. The magnetic induction remaining in a saturated magnetic material after the magnetizing field has been removed. This is the point at which the hysteresis loop crosses the B axis at zero magnetizing force, and represents the maximum flux output from the given magnet material. By definition, this point occurs at zero air gap, and therefore cannot be seen in practical use of magnet materials.C.G.S. Abbreviation for the Centimeter, Grams, Second system of measurement.Coercive Force (Hc) -The demagnetizing force, measured in Oersteds, necessary to reduce observed induction, B, to zero after the magnet has previously been brought to saturation.Curie Temperature (Tc)-The temperature at which a magnet loses all of its magnetic properties.Demagnetization Curve -The second quadrant of the hysteresis loop, generally describing the behavior of magnetic characteristics in actual use. Also known as the B-H Curve. Find these curves for some of our most popular magnet grades on ourBH Curvespage.Demagnetization Force -A magnetizing force, typically in the direction opposite to the force used to magnetize it in the first place. Shock, vibration and temperature can also be demagnetizing forces.Dimensions-The physical size of a magnet including any plating or coating.Dimensional Tolerance-An allowance, given as a permissible range, in the nominal dimensions of a finished magnet. The purpose of a tolerance is to specify the allowed leeway for variations in manufacturing.(Magnetic) Dipole Moment (m)-a quantity that describes the torque a given magnet will experience in an external magnetic field.Some folks (like physicists) use a magnetic dipole model to simulate or mathematically model a magnet or group of magnets. Mathematically, its easier than considering the complexities of weird magnet shapes. Its not theoretically perfect. Using it wont always match measured field strengths near a neodymium magnet. It works great for a sphere, but isnt correct near other shapes like discs or blocks. Its a great approximation when youre measuring far away from a magnet, but not so good close up, especially near the edges of a magnet.Calculate the dipole moment using the formulam = dipole moment in A m2= Br x V / o, where: Bris Br max, the Residual Flux Density, expressed in Tesla. Vis the volume of the magnet, expressed in cubic meters. ois the permeability of a vacuum, or 4 x 10-7N/A2.Electromagnet -A magnet consisting of a solenoid with an iron core, which has a magnetic field only during the time of current flow through the solenoid. Learn more in ourElectromagnetsarticle.Ferromagnetic Material -A material that either is a source of magnetic flux or a conductor of magnetic flux. Most ferromagnetic materials have some component of iron, nickel, or cobalt.Gauss- Unit of magnetic induction, B. Lines of magnetic flux per square centimeter in the C.G.S. system of measurement. Equivalent to lines per square inch in the English system, and webers per square meter or tesla in the S.I. system. 10,000 gauss equals 1 tesla.Gauss meter -An instrument used to measure the instantaneous value of magnetic induction, B, usually measured in Gauss (C.G.S.). Also called a DC magnetometer.Gilbert -The unit of magnetomotive force, F, in the C.G.S. system.Hysteresis Loop -A plot of magnetizing force versus resultant magnetization (also called a B/H curve) of the material as it is successively magnetized to saturation, demagnetized, magnetized in the opposite direction and finally remagnetized. With continued recycles, this plot will be a closed loop which completely describes the characteristics of the magnetic material. The size and shape of this loop is important for both hard and soft materials.With soft materials, which are generally used in alternating circuits, the area inside this loop should be as thin as possible (it is a measure of energy loss). But with hard materials the fatter the loop, the stronger the magnet will be.The first quadrant of the loop (that is +X and +Y) is called the magnetization curve. It is of interest because it shows how much magnetizing force must be applied to saturate a magnet. The second quadrant (-X and +Y) is called the Demagnetization Curve.A graphic explanation can be foundhere.Induction, (B) -The magnetic flux per unit area of a section normal to the direction of flux. Measured in Gauss, in the C.G.S. system of units.Intrinsic Coercive Force (Hci) -Indicates a materials resistance to demagnetization. It is equal to the demagnetizing force which reduces the intrinsic induction, Bi, in the material to zero after magnetizing to saturation; measured in oersteds.Irreversible Losses -Partial demagnetization of the magnet, caused by exposure to high or low temperatures, external fields, shock, vibration, or other factors. These losses are only recoverable by remagnetization. Magnets can be stabilized against irreversible losses by partial demagnetization induced by temperature cycles or by external magnetic fields.Isotropic Material -A material that can be magnetized along any axis or direction (a magnetically unoriented material). The opposite of Anisotropic Magnet.Keeper -A soft iron piece temporarily added between the poles of a magnetic circuit to protect it from demagnetizing influences. Also called a shunt. Keepers are generally not needed for Neodymium and other modern magnets. They are more commonly used with older AlnicoHorseshoe Magnets.Kilogauss -One Kilogauss = 1,000 Gauss = Maxwells per square centimeter.Magnet -A magnet is an object made of certain materials which create a magnetic field. Every magnet has at least one north pole and one south pole. By convention, we say that the magnetic field lines leave the North end of a magnet and enter the South end of a magnet. This is an example of a magnetic dipole (di means two, thus two poles).If you take a bar magnet and break it into two pieces, each piece will again have a North pole and a South pole. If you take one of those pieces and break it into two, each of the smaller pieces will have a North pole and a South pole. No matter how small the pieces of the magnet become, each piece will have a North pole and a South pole. It has not been shown to be possible to end up with a single North pole or a single South pole which is a monopole (mono means one or single, thus one pole).Magnetic Circuit -Consists of all elements, including air gaps and non-magnetic materials that the magnetic flux from a magnet travels on, starting from the north pole of the magnet to the south pole.Magnetic Field (B)-When specified on our site, the surface field or magnetic field refers to the strength inGauss. For axially magnetized discs and cylinders, it is specified on the surface of the magnet, along the center axis of magnetization. For blocks, it is specified on the surface of the magnet, also along the center axis of magnetization. For rings, you may see two values.By,centerspecifies the vertical component of the magnetic field in the air at the center of the ring.By,ringspecifies the vertical component of the magnetic field on the surface of the magnet, mid-way between the inner and outer diameters. Some depictions of magnet fields can be foundhere.Magnetic Field Strength (H) -Magnetizing or demagnetizing force, is the measure of the vector magnetic quantity that determines the ability of an electric current, or a magnetic body, to induce a magnetic field at a given point; measured in Oersteds.Magnetic Flux -Is a contrived but measurable concept that has evolved in an attempt to describe the “flow” of a magnetic field. When the magnetic induction, B, is uniformly distributed and is normal to the area, A, the flux, = BA.Magnetic Flux Density -Lines of flux per unit area, usually measured in Gauss (C.G.S.). One line of flux per square centimeter is one Maxwell.Magnetic Induction (B) -The magnetic field induced by a field strength, H, at a given point. It is the vector sum, at each point within the substance, of the magnetic field strength and the resultant intrinsic induction. Magnetic induction is the flux per unit area normal to the direction of the magnetic path.Magnetic Line of Force -An imaginary line in a magnetic field, which, at every point, has the direction of the magnetic flux at that point.Magnetic Pole -An area where the lines of flux are concentrated.Magnetomotive Force (F or mmf) -The magnetic potential difference between any two points. Analogous to voltage in electrical circuits. That which tends to produce a magnetic field. Commonly produced by a current flowing through a coil of wire. Measured in Gilberts (C.G.S.) or Ampere Turns (S.I.).Material Grade-Neodymium (NdFeB) magnets are graded by the magnetic material from which they are manufactured. Generally speaking, the higher the grade of material, the stronger the magnet. We find that the Pull Force of a magnet relates directly to the N number. Neodymium magnets currently range in grade from N35 to N52. The theoretical limit for Neodymium magnets is grade N64, though it isnt currently feasible to manufacture magnets this strong. The grade of most of our stock magnets is N42 because we feel that N42 provides the optimal balance between strength and cost. We also stock a wide range of sizes in grade N52 for customers who need the strongest permanent magnets available.Maximum Energy Product (BHmax) -The magnetic field strength at the point of maximum energy product of a magnetic material. The field strength of fully saturated magnetic material measured in Mega Gauss Oersteds, MGOe.Maximum Operating Temperature (Tmax)-Also known as maximum service temperature, is the temperature at which the magnet may be exposed to continuously with no significant long-range instability or structural changes.Maxwell -Unit of magnetic flux in the C.G.S. electromagnetic system. One maxwell is one line of magnetic flux.Magnetization Curve -The first quadrant portion of the hysteresis loop (B/H) Curve for a magnetic material.Magnetizing Force (H) -The magnetomotive force per unit of magnet length, measured in Oersteds (C.G.S.) or ampere-turns per meter (S.I). Maxwell - The C.G.S. unit for total magnetic flux, measured in flux lines per square centimeter.MGOe -Mega (million) Gauss Oersteds. Unit of measure typically used in stating the maximum energy product for a given material. See Maximum Energy Product.North Pole -The north pole of a magnet is the one attracted to the magnetic north pole of the earth. This north-seeking pole is identified by the letter N. By accepted convention, the lines of flux travel from the north pole to the south pole.Oersted (Oe) -The C.G.S. unit for magnetizing force. The English system equivalent is Ampere Turns per Inch (1 Oersted equals 79.58 A/m). The S.I. unit is Ampere Turns per Meter.Orientation -Used to describe the direction of magnetization of a material. Orientation Direction - The direction in which an anisotropic magnet should be magnetized in order to achieve optimum magnetic properties.Paramagnetic Materials -Materials that are not attracted to magnetic fields (wood, plastic, aluminum, etc.). A material having a permeability slightly greater than 1.Permanent Magnet A magnet that retains its magnetism after it is removed from a magnetic field. A permanent magnet is always on. Neodymium magnets are permanent magnets.Permeance (P) -A measure of relative ease with which flux passes through a given material or space. It is calculated by dividing magnetic flux by magnetomotive force. Permeance is the reciprocal of reluctance.Permeance Coefficient (Pc)-Also called the load-line, B/H or operating slope of a magnet, this is the line on theDemagnetization Curvewhere a given magnet operates. The value depends on both the shape of the magnet, and its surrounding environment (some would say, how its used in a circuit). In practical terms, its a number that define how hard it is for the field lines to go from the north pole to the south pole of a magnet. A tall cylindrical magnet will have a high Pc, while a short, thin disc will have a low Pc.Our onlinePull Force Calculatorcan calculate Pc for common shapes. It assumes a single magnet in free space. Other nearby magnets or ferromagnetic materials can change matters.Permeability () -The ratio of the magnetic induction of a material to the magnetizing force producing it (B/H). The magnetic permeability of a vacuum (o) is 410-7N/Amp2.Pole- An area where the lines of magnetic flux are concentrated.Plating/Coating-Most neodymium magnets are plated or coated in order to protect the magnet material from corrosion. Neodymium magnets are mostly composed of neodymium, iron, and boron. The iron in the magnet will rust if it is not sealed from the environment by some sort of plating or coating. Most of the neodymium magnets that we stock are triple plated in nickel-copper-nickel, but some are plated in gold, silver, or black nickel, while others are coated in epoxy, plastic or rubber.Polarity -The characteristic of a particular pole at a particular location of a permanent magnet. Differentiates the North from the South Pole.Pull Force-The force required to pull a magnet free from a flat steel plate using force perpendicular to the surface. The limit of the holding power of a magnet.The pull force listed is actual data acquired by testing using our state-of-the-art force test stand. A comprehensive table of the pull force for all of our stock magnets is available here:Pull Force Table.We test for two different values of pull force using two different setups. Read more about these two pull forceshere.Rare Earth Commonly used to describe high energy magnet material such as NdFeB (Neodymium-Iron-Boron) and SmCo (Samarium-Cobalt).Relative Permeability -The ratio of permeability of a medium to that of a vacuum. In the C.G.S. system, the permeability is equal to 1 in a vacuum by definition. The permeability of air is also for all practical purposes equal to 1 in the C.G.S. system.Reluctance (R)-A measure of the relative resistance of a material to the passage of flux. It is calculated by dividing magnetomotive force by magnetic flux. Reluctance is the reciprocal of permeance.Remanence, (Bd) -The magnetic induction that remains in a magnetic circuit after the removal of an applied magnetizing force.Residual F