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Introduction to Nanosensors
Published in Vinod Kumar Khanna, Nanosensors, 2021
Magnetic energy is the energy associated with magnets. A magnet is a piece of iron, steel, alloy, ore, etc., showing the property of attracting iron or similar materials called magnetic materials. Magnetic field is the region surrounding a magnetic pole, in which the magnetic force due to it is perceived. A magnetic pole is each of the two regions of a magnet from which the magnetic force appears to originate. The strength and direction of the magnetic field (H) is expressed in terms of the magnetic flux density or magnetic induction, symbol (B) defined as the magnetic flux per unit area of a magnetic field perpendicular to the magnetic force. Flux is a measure of the quantity of magnetism, taking into account the strength and extent of the magnetic field. Magnetic permeability is the ratio of magnetic flux density to the magnetizing field.
Current Trends for Actuators and Micromechatronics
Published in Kenji Uchino, Micro Mechatronics, 2019
Magnetostrictive materials convert magnetic energy into mechanical energy and vice versa. In the electronically degenerate state, the orbitals are asymmetrically occupied and get more energy. Thus, in order to reduce this extra energy, the material tries to lower the overall symmetry of the lattice, that is, undergoing distortion, which is known as Jahn-Teller distortion. In case of octahedral d-orbital configuration, the octahedron suffers elongation of bonds on the z-axis, thus lowering the symmetry. Therefore, a magnetostrictive material becomes strained according to the magnetization direction. Conversely, when either an applied force or torque produces a strain in a magnetostrictive material, the material's magnetic state (magnetization and permeability) will change. Magnetostriction is an inherent (intrinsic effect) material property that depends on electron spin, the orientation and interaction of spin orbitals, and the molecular lattice configuration, originating from the Jahn-Teller effect. It is also affected by domain wall motion and rotation of the magnetization (extrinsic effect) under the influence of an applied magnetic field or stress.18
Alternating Current (ac) Electronics
Published in Dale R. Patrick, Stephen W. Fardo, Electricity and Electronics Fundamentals, 2020
Dale R. Patrick, Stephen W. Fardo
Alternating current electrical energy is produced by placing a conductor inside a magnetic field. An experiment by a scientist named Michael Faraday showed the following important principle: When a conductor moves across the lines of force of a magnetic field, electrons in the conductor tend to flow in a certain direction. When the conductor moves across the lines of force in the opposite direction, electrons in the conductor tend to flow in the opposite direction. This is the principle of electrical power generation. Most of the electrical energy used today is produced by using magnetic energy.
Flyback converter with a stepped air-gap transformer
Published in EPE Journal, 2019
Panagiotis Mantzanas, Markus Barwig, Daniel Kuebrich, Thomas Duerbaum
Using the measurement set-up proposed in [5], the current dependent magnetizing inductance of both transformers is obtained. Figure 12 shows the corresponding results. The measurements are performed at a temperature of approximately . Due to the temperature dependent permeability and saturation flux density, the magnetizing inductance is also a function of the temperature. Nevertheless, the temperature dependence of the inductance values is negligible since the biggest portion of the magnetic energy is stored in the air-gap and the permeability has therefore a minor influence on the inductance. Thus, only the saturation currents are temperature dependent. A quite good estimation of the current dependent inductance at can be calculated by multiplying the current-axis with the ratio . Both saturation flux densities can be found in the datasheet of the core material. This estimation method for higher temperatures is verified in [16].
Energy coupled to matter for magnetic alignment of rare earth–doped alumina
Published in Materials and Manufacturing Processes, 2018
Raymond Brennan, Carli Moorehead, Victoria Blair, Krista Limmer
The anisotropic magnetic energy (ΔE), used to determine the torque acting on the system, is a function of the system properties and the applied magnetic field, as shown in Eq. (1): where V is the primary crystal volume, χa,b and χc are the magnetic susceptibilities of the crystallographic plains perpendicular and parallel to the magnetic field, respectively, µ0 is the permeability of free space, and B is the externally imposed magnetic flux density. Therefore, ΔE is a function of three factors illustrated in Fig. 1, including (a) crystal size (larger crystals undergo higher magnetic torque), (b) difference in magnetic susceptibility across different crystallographic planes (magnetically anisotropic crystals respond more strongly to a magnetic field), and (c) magnetic field strength (stronger magnetic fields lead to higher magnetic torque). In order for alignment to occur, the magnetic torque required to initiate rotation on a crystal must be larger than the thermal energy (kbT).
Quantization of magnetoelectric fields
Published in Journal of Modern Optics, 2019
For simplicity of a further analysis, we will suppose that . Assuming that quantization of magnetic energy of a ferrite-disk sample is due to quantization of the DC magnetization, the demagnetization magnetic field for a certain MDM with number n (n = 1, 2, 3, …), is found as where is a quantized DC magnetization. We can write where the mode coefficient is a dimensionless quantity: . The number corresponds to the main MDM (35).