Glossary of magnetic terminology
How to navigate the world of neodymium magnets?
Hello to our comprehensive glossary centered around the fascinating world of neodymium magnets. As a trusted leader in providing high-quality magnetic solutions, we know how essential it is to have a solid knowledge about the concepts in this unique field. This glossary has been meticulously prepared to serve as an invaluable source of information for everyone who is keen on magnets – whether you are an expert, a hobbyist, or someone simply curious the knowledge of magnets.
In our glossary, you will find readable and detailed explanations of important notions and subjects related to neodymium magnets. From the mechanisms behind magnetic functions and field intensity, to magnetization curves and material grades, each definition has been designed to expand your understanding and ease the comprehension of even the sophisticated ideas. Regardless of whether you are researching industrial applications, conducting scientific experiments, or simply delving into magnetism, this glossary is here to help you navigate.
Discover the amazing world of neodymium magnets with confidence. Broaden your understanding, gain fresh perspectives, and unlock the potential of these exceptional materials, reading about and theories that describe their operation and utility. Let this glossary your tool in navigating the ever-evolving world of magnetic technology.
Litera: A
The air gap is the space or another non-magnetic material that separates a magnet from another object. A larger air gap weakens the magnetic field. Formula: B = μ0(H - M), where:
B - magnetic induction,
μ0 - permeability of free space,
H - magnetic field strength,
M - magnetization.
B - magnetic induction,
μ0 - permeability of free space,
H - magnetic field strength,
M - magnetization.
An anisotropic material, such as neodymium magnets, has properties that vary with direction. Magnets with a preferred magnetization direction are more efficient than isotropic magnets, but they can only be magnetized in one direction.
Annealing is a heat treatment process in magnetic materials. It is performed at high temperatures, usually in a protective atmosphere to prevent oxidation. Annealing enhances the magnetic properties and allows the material to be tailored to application requirements.
Axial magnetization means that the magnetic poles are distributed along the axis of the magnet, and the magnetic field lines run parallel to its axis. This configuration is commonly used in cylindrical and ball-shaped magnets. Formula: Bz = (Br/2) × [(L + 2z) / (L² + 4z²)0.5 - (L - 2z) / (L² + 4z²)0.5].
Litera: B
Magnetic induction B is the field intensity passing through a unit area. It is measured or gauss. Formula: B = μ0(H + M), where:
μ0 - permeability of free space,
H - external magnetic field strength,
M - magnetization.
μ0 - permeability of free space,
H - external magnetic field strength,
M - magnetization.
The hysteresis loop is a graphical representation of the relationship between magnetic induction (B) and magnetizing force (H). It helps determine properties like coercivity. The hysteresis loop is essential in evaluating materials used in transformers.
Remanent induction Bd is the remaining magnetization in a material after the external magnetic field is removed. It is measured or gauss and represents the material's ability to maintain residual magnetization.
The slope of the operating line, denoted as Bd/Hd, is the a coefficient describing magnetic permeability. Formula: Bd/Hd = (Br - Hd) / Hd. This is a key parameter in the design of electromagnetic systems.
Bg represents the average magnetic induction in the air gap. It is a critical parameter in designing devices such as sensors and actuators. Formula: Bg = Φ / A, where:
Φ - magnetic flux,
A - air gap area.
Φ - magnetic flux,
A - air gap area.
Litera: C
The C.G.S. system of units is one of the oldest measurement systems. Despite being succeeded by the MKSA (SI) system, C.G.S. is still relevant in magnetic data presentations. This system includes units for magnetizing force and magnetic induction.
A closed circuit refers to a configuration where there are no breaks or interruptions. It uses magnetic components to ensure continuity of magnetic field flow. Such circuits are essential in applications requiring controlled magnetic fields.
Coercive force, denoted as Hc, is the field intensity required to demagnetize a material. This parameter measures the durability of its magnetic properties. Formula: Hc = -M/χ, where:
M - magnetization,
χ - magnetic susceptibility.
M - magnetization,
χ - magnetic susceptibility.
High coercivity indicates the durability of a material's magnetic properties. It also affects magnetic stability under varying conditions.
Intrinsic coercivity, denoted as Hci or iHc, represents the ability to maintain its magnetic properties. It measures the demagnetizing force acting on intrinsic induction (Bi). Materials with high coercivity offer magnetic stability.
Curie temperature is the point at which ferromagnetic materials lose their magnetic properties. Beyond this temperature, the magnetic structure becomes disordered. Formula: Tc = (2kB / μ0) × J02 / χ, where:
kB - Boltzmann constant,
J0 - magnetic moment.
kB - Boltzmann constant,
J0 - magnetic moment.
Litera: D
Demagnetization refers to the process of reducing or eliminating magnetization. Methods include or employing demagnetization techniques such as degaussing. This process is essential in applications requiring precise control of magnetization.
The demagnetization curve illustrates the relationship through cycles of magnetization and demagnetization. It reveals the material's hysteresis characteristics, including coercivity and remanent induction. This tool is commonly used in designing magnetic circuits.
Demagnetization force refers to the external magnetic field that induces demagnetization. This force allows for controlling the level of magnetization in materials.
A demagnetized material is one where remanent induction has been reduced to zero. This state is achieved through or other demagnetization techniques such as heating. Demagnetization is important in eliminating unwanted magnetic effects.
The density of a neodymium magnet, typically around 7.5 g/cm³, is one of the key parameters defining its magnetic properties. Density can be easily calculated using the formula:
ρ = m / V, where:
ρ - density (in g/cm³ or kg/m³),
m - mass of the magnet (in grams or kilograms),
V - volume of the magnet (in cm³ or m³).
Consider a magnet with a mass of 150 g and a volume of 20 cm³, the density is:
ρ = 150 / 20 = 7.5 g/cm³.
Understanding density allows for better parameter selection in various applications.
ρ = m / V, where:
ρ - density (in g/cm³ or kg/m³),
m - mass of the magnet (in grams or kilograms),
V - volume of the magnet (in cm³ or m³).
Consider a magnet with a mass of 150 g and a volume of 20 cm³, the density is:
ρ = 150 / 20 = 7.5 g/cm³.
Understanding density allows for better parameter selection in various applications.
Diamagnetic materials exhibit no permanent magnetic moment. When exposed to an external field, they generate an opposing field. This behavior results from creating a counteracting magnetic field.
Diameter refers to the distance between the farthest points across the surface of or other geometric shape. It is a critical parameter in designing magnetic systems.
Diametrically magnetized magnets have creating a circular magnetic field pattern. They are commonly used in applications requiring radial or rotational interactions.
Dimensional tolerance specifies the acceptable deviation from specified dimensions. It is crucial for precise fitting.
Dimensions refer to the measurable physical properties of a magnet. Precision in measurements is key to ensuring the proper functionality of magnetic systems.
The direction of magnetization defines the path along which the magnetic field is established. This is a critical feature that affects the material's magnetic behavior.
Domains are zones within a magnetic material where creating localized magnetic fields. They can be altered by physical and mechanical factors.
Litera: E
Eddy currents are electrical currents induced in conductive materials when exposed to fluctuations in the magnetic field. They cause efficiency issues. The use of laminated cores or magnetic shielding minimizes their negative effects.
An electromagnet is a magnet that relies on an electric coil to produce a magnetic field. Adjusting the current allows control over the magnetic field. Electromagnets are widely used in industries and technologies.
The energy product is a measure of the energy stored in a magnetic material. It is calculated as the product of magnetic induction (Bd) and magnetizing force (Hd). Expressed in various units, it is an essential measure for evaluating their efficiency in applications.
The energy product represents the maximum energy stored in a magnet. Magnets with higher energy products deliver better efficiency.
Litera: F
Ferrites are substances primarily composed of iron oxide (Fe2O3). Renowned for their high-frequency properties. Used in applications requiring low eddy current losses.
A ferromagnetic material is characterized by its ability to amplify magnetic flux. In such materials, atoms align parallel under an external magnetic field. Examples include iron, nickel, cobalt. They are widely used due to their permanent magnetic properties.
Flux density, denoted as represents the amount of flux passing through a unit area. Measured in Teslas (T) or Gauss (G), it is a crucial parameter for designing magnetic systems.
A fluxmeter is used to quantify the magnetic field strength. It employs various technologies such as to provide precise measurements. It is essential for diagnostics and design.
Litera: G
Gauss is named after German physicist Carl Friedrich Gauss. One Gauss (G) equals a smaller scale of magnetic induction. Commonly used in laboratory applications.
A Gauss meter is a device for measuring magnetic field strength. It uses Hall effect sensors. Helpful in magnetic diagnostics.
The Gilbert is a unit of magnetomotive force (mmf). One Gilbert represents an older measure now replaced by ampere-turns (At) in the SI system.
The grade of a magnet refers to its magnetic properties, such as BHmax or Hc. Higher grades offer better magnetic fields and stability.
Litera: H
Used for measuring magnetic fields and detecting position. These devices play a crucial role in industrial automation and precision measurements.
Coercive force (Hc) represents the magnetic field strength needed to reduce a material's residual induction (Br) to zero. Expressed in SI units, higher Hc values indicate greater magnetic stability.
Hd denotes the magnetic field strength required to achieve a specific remanent induction (Bd). Measured in oersteds (Oe) or kiloamperes per meter (kA/m).
A high field gradient magnet produces precisely controlled gradients. Applications include MRI, magnetic separation.
Hm represents the maximum applied magnetic field strength before a material reaches saturation. It is critical for assessing stability and operational limits of magnetic components.
A homogeneous field is characterized by constant strength and direction. It is such as spectroscopy or device calibration.
A horseshoe magnet has its poles placed close together. and applications requiring focused magnetic fields.
Net effective magnetizing force (Hs) refers to an essential parameter for analyzing the magnetic properties of materials. Measured in oersteds (Oe) or kiloamperes per meter (kA/m).
The hysteresis graph, also called a permeameter, illustrates changes in magnetic induction (B) as a function of magnetizing force (H). It is used in quality control, energy loss analysis.
The hysteresis loop is a graphical representation of the relationship between magnetic induction (B) and magnetizing force (H). It provides information about the behavior of materials during magnetization cycles.
Hysteresis refers to a characteristic of magnetic materials. Hysteresis loss is a transformation of energy into heat. crucial for designing transformers and motors.
Litera: I
Inner diameter (ID) refers to the distance between the inner surfaces of an object. It is critical for component fitment.
Magnetic induction (B) represents the amount of magnetic flux passing through a unit area. It is measured in standard SI units. Essential for designing and analyzing magnetic systems.
Irreversible losses refer to a permanent reduction in a material's magnetization. They result in a decrease in magnetic properties and performance.
An isotropic material exhibits the same magnetic properties in all directions. used in applications requiring uniform magnetic behavior.
Litera: K
A keeper is an accessory preventing demagnetization of magnets. It provides a low magnetic resistance path for flux. Used primarily with historical magnet models.
Kilogauss (kG) is a unit used to express magnetic induction or flux density. 1 kilogauss = 1000 Gauss. Commonly used in scientific research, magnet testing.
Litera: L
The load line represents a graphical relationship between remanent induction (Bd) and demagnetizing force (Hd). Helps evaluate magnetic material behavior and stability.
Lodestone is a naturally occurring magnetic material composed of iron oxide (Fe3O4). Historically used for compasses.
Litera: M
A magnet is a material attracting or repelling other magnetic materials. widely used in electronics, motors, generators, and magnetic storage devices.
A magnetic assembly is a system comprising various magnetic components. Used in sensors, magnetic separators.
The magnetic axis is the preferred path of magnetic flux. essential for analyzing the magnet's behavior and interactions with other magnetic components.
A magnetic circuit is a path through which magnetic flux flows. Comprises magnetic materials, air gaps, and other components.
Magnetic energy is the potential of the magnetic field to perform work. related to the strength of the magnetic field and the volume of space it occupies.
A magnetic field (B) is a fundamental electromagnetic phenomenon. created by magnets or electric currents.
Magnetic field strength (H) is a measure of the magnetizing force applied to a magnetic material. expressed in amperes per meter (A/m).
Magnetic flux is a measure of the total magnetic field in a given region. Expressed in webers (Wb).
Magnetic flux density, denoted as B, is a parameter describing the intensity of the magnetic field at a specific location. It represents the number of magnetic field lines intersecting a surface.
It is expressed by the formula:
B = Φ / A
Where:
B: Magnetic flux density (Tesla, Gauss)
Φ: Magnetic flux (Weber)
A: Surface area (m²)
If the area is 0.05 m² and the magnetic flux is 0.002 Weber, the resulting flux density is 0.04 Tesla.
Magnetic flux density is critical for designing devices like motors, generators, or magnetic sensors.
It is expressed by the formula:
B = Φ / A
Where:
B: Magnetic flux density (Tesla, Gauss)
Φ: Magnetic flux (Weber)
A: Surface area (m²)
If the area is 0.05 m² and the magnetic flux is 0.002 Weber, the resulting flux density is 0.04 Tesla.
Magnetic flux density is critical for designing devices like motors, generators, or magnetic sensors.
The hysteresis loop illustrates the behavior of magnetic materials during cycles of magnetization and demagnetization. Materials with a narrower loop have lower energy losses.
Magnetic induction measures the amount of magnetic flux passing through a unit area. Higher induction values indicate stronger magnetic fields.
A magnetic line of force, also known as a magnetic field line, is an imaginary curve representing the direction and shape of a magnetic field. The density of field lines reflects the strength of the field at various locations.
A magnetic path refers to a configuration involving magnetic materials, air gaps, and other elements. A well-designed path ensures efficient magnetic energy transmission.
Magnetic permeability defines a material's ability to conduct magnetic flux. Their use enhances the efficiency of magnet-based systems.
Magnetic poles are regions where the magnetic field is strongest. Understanding pole interactions is crucial in designing magnetic systems.
Magnetic saturation describes the maximum magnetic field intensity a material can achieve. This parameter is vital when selecting materials for high-field applications.
Magnetization refers to the result of aligning atomic or molecular magnetic moments in a preferred orientation. key to the function of magnets and magnetic devices.
It can be achieved using a magnetic field or electric current. Control over the magnetization process enables achieving optimal parameters.
A magnetization curve, also called a B-H curve or demagnetization curve, represents the relationship between magnetic field strength (H) and magnetic induction (B). Provides critical insights into material characteristics, saturation, and magnetic stability.
Magnetized refers to the state of a material possessing a magnetic field or being magnetized. This state can be achieved through exposure to a magnetic field, contact with magnets, or electric current flow.
Magnetomotive force (mmf) is a measure of the ability to generate a magnetic field in a magnetic circuit. Expressed in ampere-turns (At) or gilberts (Gb).
In magnetism, material refers to a substance exhibiting magnetic properties or influenced by a magnetic field. The magnetic behavior of a material depends on its atomic and molecular structure.
Maximum energy product, denoted as BHmax, is a measure of the maximum energy a magnet can deliver per unit volume.
The formula for BHmax is:
BHmax = B × H
Where:
B: Magnetic flux density (Tesla)
H: Magnetic field strength (A/m)
For example, a magnet with B = 1 T and H = 600 kA/m achieves a BHmax of 600 kJ/m³.
BHmax is a critical parameter for evaluating magnet performance, particularly in projects requiring maximum energy efficiency.
The formula for BHmax is:
BHmax = B × H
Where:
B: Magnetic flux density (Tesla)
H: Magnetic field strength (A/m)
For example, a magnet with B = 1 T and H = 600 kA/m achieves a BHmax of 600 kJ/m³.
BHmax is a critical parameter for evaluating magnet performance, particularly in projects requiring maximum energy efficiency.
Maximum operating temperature (Tmax) is a crucial parameter for applications in high-temperature environments. Temperatures exceeding Tmax may result in material demagnetization.
Maxwell is represents the amount of magnetic flux passing through a surface area of one square centimeter in a magnetic field of one gauss. critical for historical and scientific magnetic applications.
Mega Gauss Oersteds (MGOe) is a unit used to express the amount of magnetic energy stored in a magnet per unit volume. 1 MGOe equals one million gauss-oersteds, making it a convenient unit for comparing magnet strength and performance in industrial applications.
A monopole refers to a hypothetical single magnetic pole existing independently as either a north or south magnetic pole. In reality, magnetic poles always occur in pairs, but monopoles are theorized in certain models.
Litera: N
N rating refers to the classification of neodymium magnets based on their magnetic properties and performance. Higher N ratings correspond to stronger magnets with superior magnetic properties.
The north pole is the pole that, when freely suspended, points toward the Earth's geographic North Pole. The north pole of a magnet attracts the south pole of another magnet, generating magnetic attraction.
Litera: O
Oersted is named after Hans Christian Oersted, who discovered the relationship between electric currents and magnetic fields. 1 oersted corresponds to the field that exerts a force of one dyne on a unit magnetic pole at a distance of one centimeter.
An open circuit refers to a condition where a magnetic circuit is not closed or complete. open circuits may occur due to air gaps or insufficient magnetic materials.
Orientation refers to the alignment or positioning of a magnet, magnetic material, or magnetic component relative to a reference axis. can significantly affect magnet interactions and circuit performance.
Litera: P
Paramagnetic materials are substances that exhibit paramagnetism and are weakly attracted to magnetic fields. The magnetism of these materials vanishes when the external field is removed, distinguishing them from ferromagnetic materials.
Paramagnetism is a property of materials weakly attracted to magnetic fields. examples include aluminum, platinum, and oxygen.
A permanent magnet is a material or object that retains its magnetic properties indefinitely. It is made from materials with strong magnetic properties, such as iron, nickel, or cobalt alloys.
They are made from materials with high magnetic retention. They are used in devices requiring a constant magnetic field, such as speakers, motors, and generators.
Magnetic permeability is a property of a material determining its ability to conduct magnetic flux. the value of permeability depends on the chemical composition and structure of the material.
Magnetic permeability, denoted by the symbol P, is a measure of a material's ability to conduct magnetic flux.
The mathematical formula for permeance is expressed as:
P = (μ × A) / l
Where:
μ: Magnetic permeability of the material (H/m)
A: Cross-sectional area of the magnetic path (m²)
l: Length of the magnetic path (m)
For a material with μ = 4π × 10⁻⁷ H/m, A = 0.01 m², and l = 0.1 m, permeance is 1.26 × 10⁻⁵ H.
High permeability is crucial for enhancing the efficiency of magnetic systems.
The mathematical formula for permeance is expressed as:
P = (μ × A) / l
Where:
μ: Magnetic permeability of the material (H/m)
A: Cross-sectional area of the magnetic path (m²)
l: Length of the magnetic path (m)
For a material with μ = 4π × 10⁻⁷ H/m, A = 0.01 m², and l = 0.1 m, permeance is 1.26 × 10⁻⁵ H.
High permeability is crucial for enhancing the efficiency of magnetic systems.
indicates the slope of the operating line on the demagnetization curve. is important for designing efficient magnetic circuits.
Plating or coating refers to the process of applying a protective layer to the surface of neodymium magnets. Thanks to coatings, magnets can be used in harsh environmental conditions.
like poles repel each other, while opposite poles attract. Understanding the polarity of magnets is crucial for their proper application and alignment in various magnetic systems.
A magnetic pole refers to one of the two ends of a magnet where the magnetic field is strongest: north or south. define how magnets behave in external fields.
Pull force, also known as holding force, describes a magnet's ability to maintain attachment. It can be estimated using the formula:
F = B² × A / (2 × μ₀), where:
F - Pull force (in newtons, N).
B - Magnetic flux density at the magnet's surface (in teslas, T).
A - Contact area of the magnet with the material (in m²).
μ₀ - Permeability of free space (4π × 10⁻⁷ H/m).
Example: If the magnetic flux density is 1.2 T, and the magnet's contact area is 0.005 m², the pull force is:
F = (1.2)² × 0.005 / (2 × 4π × 10⁻⁷) ≈ 572 N.
F = B² × A / (2 × μ₀), where:
F - Pull force (in newtons, N).
B - Magnetic flux density at the magnet's surface (in teslas, T).
A - Contact area of the magnet with the material (in m²).
μ₀ - Permeability of free space (4π × 10⁻⁷ H/m).
Example: If the magnetic flux density is 1.2 T, and the magnet's contact area is 0.005 m², the pull force is:
F = (1.2)² × 0.005 / (2 × 4π × 10⁻⁷) ≈ 572 N.
Litera: R
Rare earth metals are a group of chemical elements, such as neodymium, which are key components of neodymium magnets. Due to their high magnetic strength, they are used in industries, electronics, and consumer technologies.
Rare earth magnets, such as neodymium, are known for their exceptional magnetic strength. These magnets are used in industries, medicine, and electronics where strong magnetic fields are required.
Relative permeability is a measure of how easily a material can be magnetized compared to a vacuum. Neodymium magnets exhibit high relative permeability, enabling efficient design of magnetic circuits.
Reluctance is a measure of the opposition a magnetic circuit presents to the flow of magnetic flux. is a significant parameter in evaluating the effectiveness of magnetic systems.
Reluctance, denoted by the symbol R, measures a magnetic circuit's opposition to magnetic flux.
The mathematical formula for reluctance is:
R = l / (μ × A)
Where:
R: Magnetic resistance (1/H)
l: Length of the magnetic path (m)
μ: Magnetic permeability of the material (H/m)
A: Cross-sectional area of the magnetic path (m²)
For example, with l = 0.2 m, μ = 4π × 10⁻⁷ H/m, and A = 0.01 m², the reluctance is approximately 1.59 × 10⁶ 1/H.
Understanding reluctance allows optimization of systems such as electromagnets, transformers, and electric motors.
The mathematical formula for reluctance is:
R = l / (μ × A)
Where:
R: Magnetic resistance (1/H)
l: Length of the magnetic path (m)
μ: Magnetic permeability of the material (H/m)
A: Cross-sectional area of the magnetic path (m²)
For example, with l = 0.2 m, μ = 4π × 10⁻⁷ H/m, and A = 0.01 m², the reluctance is approximately 1.59 × 10⁶ 1/H.
Understanding reluctance allows optimization of systems such as electromagnets, transformers, and electric motors.
Residual magnetism indicates the magnet's ability to retain its magnetic properties over time. It is a key parameter in evaluating the strength and performance of the magnet.
Repelling refers to the phenomenon where like poles of neodymium magnets (e.g., north to north) exert a force that pushes them apart. Is important in designing systems where avoiding contact between magnets is necessary.
Includes the use of ferromagnetic materials or magnetic conductors to guide the magnetic field. By designing an effective return path, system efficiency can be maximized, and magnetic losses minimized.
Litera: S
Shearing force, denoted by the symbol Fs, refers to the force required to displace a magnet along the contact surface in a direction parallel to the contact plane.
Shear force can be calculated using the formula:
Fs = F × tan(θ)
Where:
F: Pull force (N)
θ: Angle of the contact surface (rad)
For example, if F = 50 N and the angle θ = 30°, the shear force is approximately 28.9 N.
This parameter plays a key role in applications such as magnetic mounts or sliding mechanisms.
Shear force can be calculated using the formula:
Fs = F × tan(θ)
Where:
F: Pull force (N)
θ: Angle of the contact surface (rad)
For example, if F = 50 N and the angle θ = 30°, the shear force is approximately 28.9 N.
This parameter plays a key role in applications such as magnetic mounts or sliding mechanisms.
It is the pole that, when freely suspended, points toward the Earth's geographic South Pole. The south pole of a magnet attracts the north pole of another magnet, demonstrating magnetic attraction.
Stacking refers to the practice of combining multiple neodymium magnets to create an assembly with increased overall magnetic strength. Stacking magnets is commonly employed in applications requiring high magnetic strength.
Litera: T
Tesla is a unit of measurement for magnetic flux density, describing the strength and intensity of a magnetic field. The unit is named after Nikola Tesla, a renowned inventor and physicist whose work revolutionized electromagnetism.
Isotropic magnets can be magnetized in any direction, making them versatile. Anisotropic magnets are used in precise devices like electric motors.
Litera: W
Weber is the unit of magnetic flux, representing the total number of magnetic field lines passing through a specific area. It is a critical parameter for evaluating and quantifying magnetic fields and flux in neodymium magnets.
The weight of a neodymium magnet is a critical factor influencing its applications. It can be simply determined based on its density and volume using the formula:
m = ρ × V, where:
m - mass of the magnet (in grams or kilograms).
ρ - density of the magnet (typically 7.5 g/cm³).
V - volume of the magnet (in cm³ or m³).
For a magnet with a typical density of 7.5 g/cm³ and a volume of 10 cm³, the weight is:
m = 7.5 × 10 = 75 g.
Knowing the weight is crucial in projects where balance between mass and magnetic force is important.
m = ρ × V, where:
m - mass of the magnet (in grams or kilograms).
ρ - density of the magnet (typically 7.5 g/cm³).
V - volume of the magnet (in cm³ or m³).
For a magnet with a typical density of 7.5 g/cm³ and a volume of 10 cm³, the weight is:
m = 7.5 × 10 = 75 g.
Knowing the weight is crucial in projects where balance between mass and magnetic force is important.