Bh curve lab manual. pdf), Text File (.
Bh curve lab manual. Jun 28, 2021 · View Manual of B-H CURVE (1). H Curve Apparatus B. Repeat the measurement and plotting process for different AC excitation frequencies and amplitudes. May 8, 2015 · This experiment covers B-H curves of magnetic material and inductor design through identifying unknown design factors. 5 B – H curve Aim : To study B-H curve and to find out the values of coercivity, retentivity and saturation magnetisation of experimental material. Key points on the loop include saturation, where additional field strength does not increase flux density, and retentivity, where some 5 days ago · The graph intensity of magnetization (M) vs. B-H Curve Hysteresis Loop Lab Manual Compiled By Dr. Compare the B-H curves obtained with the published literature for the material. The study is well supported by the “WEISS DOMAIN” theory. 8 Hysteresis Curve The circuit below, from Physics Demonstration Experiments Volume 2 by Harry Meiners, page 972, will draw a hysteresis curve on the oscilloscope. pacitance and the inductance of the pickup loop. Consider the portion AB of the curve given below. Samples like nails, ferrite rods, and transformer stampings are inserted in the magnetizing coil and their hysteresis loops are displayed on an oscilloscope by varying the voltage. Please Like and Subscribe. CURVE BOARD M/s TEXLA SCIENTIFIC INSTRUMENTS #3-3-593, CHAPPAL BAZAR, HYDERABAD – 500 027 MOBILE: 9440108331, 98480 71461, TELEFAX: 040- 24652326 CAT No: 1298 email ID- mail2texla@gmail. The B-H analyzer is the only device that can measure the core loss of a wide range of B-H curves with high accuracy, from low frequencies to high frequencies in the MHz band under all conditions. s cord te the instrument (Hysteresis Loop F racer) on the back side. A transformer is used to generate a magnetic field by passing a current through the primary coil, and the induced voltage in the secondary coil is measured to calculate the magnetic flux density B. Most ma- terials are provided with data sheets that contain BH-curves or comparable data tables. It includes procedures for installing and uninstalling the software, conducting B-H curve experiments, and calibrating sensors. , LTD. Connecting equipment like an auto transformer, oscilloscope, and integrator in a circuit to generate the B-H loop. Access 20 million homework answers, class notes, and study guides in our Notebank. H Curve Apparatus Kit measures and studies the magnetic properties of materials. 11. The B-H curve of a magnetic element, such as an inductor or transformer, is a characteristic of the magnetic material forming the core around w Download our bh curve experiment viva eBooks for free and learn more about bh curve experiment viva. When we decrease resistance,the current value increases and as a result the thickness of B-H loop increases. The twenty ohm resistor serves to measure the current to the transformer primary producing a horizontal signal proportional to H. Fig. scientific equipment supplier, educational equipment. It details the aim, apparatus, circuit diagram, theoretical background on hysteresis in ferromagnetic materials, and the procedure for 5 days ago · The graph intensity of magnetization (M) vs. be!òre switch the Hysteresis Loop racer, connect din connector cable oi- sa:npie holder to the Inpu$ of the Hysteresis Loop Tracer. The document describes an experiment to obtain a hysteresis curve for a ferromagnetic material using an oscilloscope. Curve Apparatus goes through various quality inspections to ensure that it is free from any defects. The experiment can be repeated with different resistances to analyze variations in This document describes how to draw and analyze a hysteresis (B-H) curve for a ferromagnetic material sample. TRACING HYSTERESIS CURVE OF A TRANSFORMER CORE USING B-H CURVE Aim: To trace hysteresis curve of a transformer core using a CRO and find the energy loss per unit volume per cycle, coercivity and retentivity of the material core. 28 There are two methods to determine the B-H curve of a specimen: the method of reversal and the step-by-step method. EXPERIMENT 8 CALCULATION OF IRON LOSSES USING B-H CURVE USING OSCILLOSCPE magnetic specimen using a cathode ray oscilloscope(CRO) and to evaluate the en APPARATUS:CRO, capacitors, resistors, multi meter and core of the transformer. Magnetic performance parameters such as coercive force Hcj and maximum magnetic energy product BHmax, and display BH hysteresis loop and demagnetization curve. Tech. Study the variation of B versus H by magnetizing the magnetic material (B-H curve) Determination of ultrasonic velocity in liquid (Acoustic grating) Rigidity modulus of material of a wire-dynamic method (Torsional pendulum) Sonometer: Verification of the three laws of stretched strings B. The document describes an experiment to measure and plot the B-H curve and permeability curve of a given material using a data logger, power supply, coils, cores and sensors. amrita. Results indicated that soft iron is ideal for electromagnets due to low loss, while steel is suited for permanent magnets due to high coercivity, and ferrite is appropriate for high-frequency applications. H curves representing the relationship between magnetic field strength (H) and magnetic induction (B). j “ol ot 2 coll consisting of a core of ordinary steel, the B-H or ma: oe 5 INSTRUCTION MANUAL FOR BH CURVE APPARATUS made BH Curve Apparatus hias been designed to plot the BH curve for the sample coil provided inside the cabinet The instrument comprises of the following built in parts. B; Devine, M. Properties like retentivity, coercivity, and hysteresis loss can be determined from the curve. B-H Curve This curve shows the effect of variation in Load current over B-H loop. EXPERIMENT 1 MAGNETIC CIRCUIT OBJECTIVES 1. The document describes an experiment to obtain the B-H loop and magnetization curve for a magnetic core and determine the core losses. Sample holder securely positions 1. \ (\vec {\text Determination of BH - Free download as Word Doc (. This is done by pressing the Plot B-H Curve button or the Log Plot B-H Curve button on the B-H data dialog. Terminals are provide for x & y plates. To obtain result for total Measurement of magnetic susceptibility by Gouy’s method . Whenever possible, make a comparison between the data obtained in your experiment and published data. , , Apparatus Required:, B-H curve tracer kit,, CRO, Patch Cords,, Trace paper Magnetic Materials: Nail,, Hack Saw Blade,, Ferrite Rod,, Steel rod, , Theory:, The lag or delay of a magnetic material known DX-2012H DC Hysteresis Graph Test System is a BH Loop tracer to measure the remanence Br, coercive force Hcb, internal magnetism of various ferrites, alnico, neodymium iron boron and samarium cobalt and other permanent magnetic materials. Universal B-H Curve Tracer is a self contained instrument and need any low cost C. Techstudents of Marri Laxman Reddy Institute of Technology and Management, Dundigal, Hyderabad. fObjectives The goal of this lab exercise is to study the phenomena of magnetic hysteresis for an iron core using a hysteresis loop Holmarc’s B-H curve experiment model no: HO-ED-EM-09 is used for the analysis of the magnetic hysteresis loop / B-H curve for soft iron & laminated iron cores used in two coils bound electromagnet with DC current supply. 1st Year Physics Laboratory Experiment No. The required setup and the necessary calculations are in this file. 2 User’s Manual David Meeker dmeeker@ieee. H, see Figure (6. org August 25, 2013 Chapter 1 Introduction FEMM is a suite of programs for solving low frequency electromagnetic problems on two-dimensional planar and axisymmetric domains. pdf from PHYSICS 1234567899 at Manarat Alriyadh International School. 1, AC stey down transformer of 3V AC to 18V AC in the steps of 3 volt. A: Magnetizing fore or Magnetic field intensity at any point in a magnetic field is the magnitude of the force experienced by a unit pole situated at that point. User manual for Hysteresis Loop Tracer (Model: HLT-111) Jiles, D. doc), PDF File (. It describes the apparatus components, including the solenoid and circuit setup, along with the theoretical background and procedure for conducting the experiment. 4 days ago · The lag or delay of a magnetic material known commonly as Magnetic Hysteresis. In this video, we perform the BH curve experiment using an oscilloscope, a key practical for graduation and BS Physics students, and a stepping stone for engineering physics. Sivaram Prasad 768 subscribers 1. Jan 14, 2021 · This link provides you the handwritten practical file of the BH curve (Hysteresis loop) experiment with readings. It also defines various terms related to magnetism and the B-H curve, such as magnetic field intensity, magnetic induction, permeability, and susceptibility. Lab Manual Of Bh Curve: Laboratory Manual in Applied Physics H. A hysteresis curve shows the relationship between magnetic flux density (B) and magnetizing force (H). Sathyaseelan,2002 Introduction Torsional Pendulum Compound Pendulum Laser Grating Determination Of Wavelength Optical Fibres Measurement Of Numerical Aperture Optical Fibres Attenuation In Fibres Spectrometer Refractive Index Of Prism Spectrometer I D Curve O Air Wedged Hysterisis Energy Loss Of Ferrites B H Curve Energy Loss Of Explore ferromagnetic hysteresis with this lab manual. For a B_H_Curve - Free download as PDF File (. You should see a B-H curve that looks something like the curve pictured in Figure 2. 9K Dec 26, 2018 · 1. Learn to plot M vs. Discover high-quality scientific instruments and services. The document is a user manual for the B-H Curve Trainer, detailing the procedure to trace the B-H loop of a ferromagnetic specimen using a cathode ray oscilloscope (CRO). The experiment uses a CRO, specimen wire, power supply, AC voltmeter and ammeter. It is ideal for new product development and product inspection in R&D departments, quality assurance departments, and manufacturing departments of material, core, parts, and equipment BH Curve Loop / Magnetic Hysteresis Loop Tracer Physics Experiment Apparatus manufacturer supplier and exporter of physics lab equipment models India. To draw hysteresis (B-H curve) of a specimen in the form of a transformer and to determine its hysteresis loss Jun 21, 2024 · How to use a digital oscilloscope to produce the dynamic B-H Curve of magnetic components? Keywords: Magnetic components, B-H Curve, Magnetic saturation Preface: This article will elaborate how to use a digital oscilloscope to produce magnetic flux density (B) and magnetic field strength (H), and discuss the differences between static (Sine Wave) B-H curve measurement and dynamic excitation This document introduces the BHmag database, which contains approximately 300 digitized B-H curves of almost all known magnetic materials. It is generated by measuring B while changing H. B-H curve - Determination of the hysteresis energy loss Dr. H using resistance , capacities & inductance step down transformer 2-12 volt AC. (commercial Nickel). Experiment No Aim: To study the B-H curve for given ferromagnetic materials and find their Experiments for B. Measuring and plotting the magnetic flux density (B) and magnetic field strength (H) to obtain the hysteresis loop on an If an alternating magnetic field is applied to the material, its magnetization will trace out a loop called a hysteresis loop or B-H Curve. He described how applied magnetic fields provide energy to move domain walls past pinning sites Get help with homework questions from verified tutors 24/7 on demand. The step-by-step method uses a potential divider with many The AMH-500 BH-tracer is a DC automatic measuring system for the characterization of hard magnetic materials: alnico, ferrites, NdFeB, SmCo. Study of the hysteresis curve as a function of the magnetic field. We deliver it within a promised time frame. The output of the secondary of the transformer is proportional to dB/dt. It makes use of a specially designed integrated circuit probe to measure the flux density B. B-H Curve | Viva Voce | Retentivity & Coercivity | Practical File All Lab Experiments 68. The areas of each loop and enclosing rectangle are B-H analyzer - IWATSU ELECTRIC CO. Apparatus Used : Set up for B-H curve, experimental material (commercial Nickel), CRO, connecting leads. The remote trigger equipment allows you to control the applied magnetic field (H). The document summarizes an experiment to draw and compare the B-H curves of different iron core samples. The database is organized into 11 categories of magnetic materials, with each category containing multiple BH files with the magnetization curve, permeability curve, and other data for that material. Step by step explanation has been given for a clear understanding. H is the internal magnetic field: its sources include \ (\rho_ {m}=-\operatorname {div} (\vec {\text {M}})\) in the magnetic body as well as any externally applied magnetic field generated by a system of coils outside the magnetic body. Muhammad Asim Rasheed **This manual has been compiled and adopted from various resources like Wikipedia and some other lab manuals on the internet which were then modified to meet requirements of this lab. The method of reversal involves demagnetizing a ring specimen and bringing it into a reproducible cyclic state by reversing a switch 20 times at each magnetizing current value to measure the corresponding flux density. The initial value of resistance is high and BH loop seems as a straight line. Bh Curve - Free download as PDF File (. Full Name: To draw hysteresis (B-H curve) of a specimen in the form of a transformer and to determine its hysteresis loss - virtual-lab Dhrumilkumar Panchal presented a seminar on magnetic hysteresis for his first semester of computer engineering in 2017-2018. Apparatus: B-H Curve unit, ferrite core, CRO, translucent paper etc. Key steps include: 1. High garde raw material and ultra modern machinery is used in its fabrication under the guidance and supervision of experts. , “OR”, , AIM-To trace hysteresis loop for different magnetic materials. Retentivity is the Jan 8, 2022 · Page 1 : Experiment Number-1, AIM-Determine the permeability of magnetic material by plotting its B-H, curve. 1 shows the circuit used. docx from MEC 211 at Universiti Teknologi Mara. 3). 3. Power supply unit adjusts the current to control the magnetic field intensity. After you are done entering in your B-H data points, it is a good idea to view the B-H curve to see that it looks like it is “supposed” to. The document outlines Experiment 8 of the Electrical Measurements and Instrumentation Lab, focusing on calculating iron losses using the B-H curve and an oscilloscope. pdf - Free download as PDF File (. The characteristics which are usually used to define the quality of the substance are coercivity, retentivity, saturation magnetisation and hysteresis loss. C: Thoelke, J. Thus the intensity of magnetization M at every stage lags behind the applied field H. CIRCUIT DIAGRAM: The graph intensity of magnetization (M) vs. Connect the mai;. The experiment involves setting up a BEE Viva - Free download as PDF File (. You can compare all these curves to discover the manufacturer that produces the grade that is optimal for your machine. The experiment Take sample holder and insert a ferromagnetic sample in the lower side. Theory Introduction A precise knowledge of various 4 Report ot data of B H curve using MATLAB/gnuplot or any oth Can you obtain value of permeability with this data? If yes, derive formula for the same. O having X-Y gain. Calculation of Hysteresis Loss: The hysteresis loss can be calculated using the area enclosed by the B-H curve. The B-H curve, also known as the magnetization curve or hysteresis loop, is a graphical representation of the relationship between the magnetic flux density (B) and the magnetic field strength (H) in a magnetic material. Lab manual of bh curve cptaating insti rsncn omega tine od page al) omnan nir es dab fr elit hard hine com doiigrad npwcifenlhy mir the oemonatrwbcn nh no age In this video I explained how to perform the experiment of B H curve for a given ferromagnetic material. This document presents information about magnetic hysteresis and the B-H curve. These books contain exercises and tutorials to improve your practical skills, at all levels! To find more books about bh curve experiment viva, you can use related keywords : Bh Curve Experiment Viva, Titration Curve Experiment Lab Report, Barton's Experiment Viva, Viva On Melde's Experiment May 26, 2021 · Demonstration of B-H Curve experiment with data and calculations Lab report curve curve jyothis chandran1 ims15075 iiser thiruvananthapuram (dated: 18 october 2018) precise knowledge of various magnetic parameters of Mar 5, 2022 · The magnetic properties of ferromagnets at a fixed temperature are often described by curves of magnetic induction B vs. It explains that the hysteresis curve is a plot of magnetic flux density B versus magnetic field intensity H that shows the lag of B behind H as it changes. This experiment aims to study the B-H (magnetic flux density-magnetic field strength) curve for ferromagnetic materials to determine their coercivity and retentivity. BH-curve. This dependence arises because the system can be in more than one They contain 634 B(H) magnetization curves and 589 core loss curves. O. It outlines the steps for connecting the circuit, adjusting the CRO settings, and estimating the energy loss by tracing the hysteresis loop. The final RC circuit Explore the B-H curve apparatus at Kamaljeeth Instruments. Then the B-H curve follows the path of a-b-c-d-e-f-a as the magnetising current flowing through the coil alternates between a positive and negative value such as the cycle of an AC voltage. Clients can avail it from us at cost- effective prices. Additionally, it provides insights into ferromagnetism at the atomic level and Main Magneization curve approximation online Magneization curve approximation Magnetic properties of ferromagnetic materials vary with temperature, and the magnetization or B-H curve (also called hysteresis curve) may be different at different temperatures. It describes how the instrument works to measure and trace the hysteresis loop of ferromagnetic materials by applying an alternating magnetic field and measuring the flux density. The experiment aimed to plot B-H curves for various magnetic materials (soft iron, steel, ferrite) to analyze their magnetic properties such as coercivity and retentivity. In this technique, B-H loop is formed by simply inserting the specimen in a magnetizing coil. edu OPERATING INSTRUCTIONS FOR APPARATUS TO DETERMINE FERROMAGNETIC CONSTANTS: RETENTIVITY, PERMEABILITY AND SUSCEPTIBILITY BY TRACING B-H CURVE OBJECT : To determine the ferromagnetic constants: retentivity, permeability and susceptibility by tracing B-H curve. Key magnetic properties The purpose of the experiment is to obtain a series of deflections, corresponding to known changes of primary current, from which to plot a curve whose coordinates are proportional to the values of Bapp and B in the iron. M. B-H loops are traced at different voltages and currents. 27-28, Vol. This document contains questions and answers related to experiments conducted to verify Kirchhoff's law, study the superposition theorem, plot the B-H curve of a transformer, determine the resistance and inductance of a choke coil, study R-L-C series and parallel circuits, perform open and short circuit BH curve tracing is used to analyze ferromagnetic materials by measuring their coercivity, retentivity, and saturation magnetization. com fTEXLA SCIENTIFIC INSTRUMENTS CAT No: 1298 B. The objectives are to familiarize with magnetic circuits, understand B-H curves and magnetic saturation, and compare the relative permeabilities of magnetic materials. Constructs B. pdf), Text File (. This presentation discusses the B-H hysteresis curve of ferromagnetic materials. B. BH-curve - Free download as PDF File (. The program currently addresses linear/nonlinear magnetostatic problems, linear/nonlinear time harmonic magnetic problems, linear Apr 6, 2019 · View LAB REPORT ELE. H curve to trace hysteresis curves on C. Because of the lengthy The BH curve experiment involves studying the magnetic properties of a material by examining its magnetization behavior under varying magnetic field strengths. R. MANUAL B. Resistance Control: completed the term of the subject, Engineering Physics Lab-II, 6 days ago · The lag or delay of a magnetic material known commonly as Magnetic Hysteresis. Abstract – This brief discusses the measurement of the BH curve and iron loss characteristics of magnetic materials based on tests on cores done at mains frequency. H. A: The number of The BH curve, also known as the magnetization curve or hysteresis loop, is a graphical representation of the relationship between magnetic field strength (H) and magnetic flux density (B) in a magnetic material. Plotting the B-H curve: Plot the B-H values on a graph with B on the vertical axis and H on the horizontal axis. BH Curve Loop / Magnetic Hysteresis Loop Tracer Physics Experiment Apparatus manufacturer supplier and exporter of physics lab equipment models India. Key points: 1. insert this sample holder in the solenoid. The load current changes with external resistance. Physics experiment guide. google. Home » Universal B-H Curve Tracer Universal B-H Curve Tracer Theory In the conventional techniques of tracing the B-H loop, one has to wind a primary and a secondary coil on the specimen and experiment with it. The experiment E. It involves using a hysteresis loop tracer to generate magnetic hysteresis loops, which plot flux density (B) against field strength (H). Connect solenoid to Solenoid socket of Hysteresis Loop Tracer See full list on vlab. It also discusses three methods for measuring iron loss in ferromagnetic materials: the wattmeter method, bridge method, and potentiometer method Feb 22, 2022 · To verify the B-H curve and the hysteresis loop for a given sample in the form of an anchor ring. It forms a hysteresis loop where the area inside represents energy lost due to magnetic hysteresis during the magnetization and demagnetization process. This path is called a Magnetic Hysteresis Loop. Furthermore, the understanding of the behaviour of these substances and improvement in their quality demand that the number of magnetic phases present in a system is also known. Manual_of_B_H_CURVE__1_. This dependence arises because the system can be in more than one Understanding the Hysteresis (BH) Curve Hysteresis curves, also called B-H curves, describe the Intrinsic and Normal magnetic properties of a material. His presentation explored the physics behind ferromagnetic hysteresis, including how crystal imperfections pin domain walls, causing irreversible behavior known as hysteresis. All lab manual: https://drive. lab 1. Finite Element Method Magnetics Version 4. magnetizing field (H) gives a closed curve called M-H loop. Step 3: Click on probe to placing the probe in between the solenoid in the simulator. 2. This allows identification of magnetic phases present and determines how a material's magnetization changes as the external . May 22, 2022 · This link provides the lab manual used for B-H curve loop tracing using CRO. Includes an electromagnet or solenoid as the primary source of the magnetic field. The main objective of the Engineering Physics Lab Manual is to furnish the conceptual understanding of the basic principles. Magnetic permeability measurement Core materials used for motors, actuators, and relays include silicon steel, soft steel, and permalloy. 2 One simple of coil is kept inside BH-Curve: The plot of Hysteresis is known as a B-H curve, where B (The Material's Flux Density, measured in Teslas or Mega Gauss) is plotted on the vertical axis and H (The External Applied Magnetizing Force, measured in Amperes per meter) is plotted on the horizontal axis. The Hysteresis curve is commonly seen in supplier catalogs as a second quadrant curve showing Br, Hc, Hci and BH(max). Key points covered include: 1. com/drive/u/1/folder Step 1: To measure the magnetic field generated in the solenoid Step 2: Select Magnetic field Vs Current from the procedure selection-box. The document is an instruction manual for the B-H Curve Apparatus, detailing the experiment to trace the B-H curve for ferromagnetic materials using a CRO. The manual also includes instructions for making connections and adjusting 5 days ago · Procedure Lab Experiment Overall Goals The goal of this lab exercise is to study the phenomena of magnetic hysteresis and calculate the retentivity, coercivity and saturation magnetization of a material using a hysteresis loop tracer (HLT-111). An The B-H curve plots the magnetic flux density (B) and magnetic field strength (H) of a magnetic material. K: “Numerical Determination of Hysteresis Parameters for the Modeling of Magnetic Properties Using theTheory of Ferromagnetic Hysteresis†, IEEE Transactions on Magnetics, pp. To obtain the B-H curve for a single-phase transformer. The document explains hysteresis and Physics lab: Viva-Voce Question and Answers 1. It discusses different types of magnetic materials, including diamagnetic, paramagnetic, and ferromagnetic substances. The document is an instruction manual for using the B-H Curve with computer software INDOSAM, detailing the basic theory of magnetic induction in transformers and the setup for experiments. Define magnetizing force (H). This document describes an experiment to measure hysteresis loss in a ferromagnetic material over a complete cycle. H curves, calculate retentivity & coercivity. B-H Curve What is a magnetic field? A: Magnetic field is the region where a magnetic pole experience a force. The document describes two methods for determining the B-H curve of a ring specimen: the method of reversal and step-by-step method. - Free download as PDF File (. You should see a B-H curve that looks something like the curve pictured in Figure 12. Accurately measure the AC magnetic properties of soft magnetic materials up to high frequencies This device measures the AC magnetic properties of soft magnetic materials. PREFACE This book entitled “Applied Physics Lab Manual” is intended for the use of First year B. 3K subscribers 668 Roorkee - 247 Physics Laboratory IIT Delhi tween B (H) we can produce a set of curves known as magnetization curves or mag- netic hysterisis curves or simply BH curves. 2. This is done by pressing thePlot B-H Curve button in the B-H data dialog. An apparatus is used that includes a B-H curve tracer, specimen solenoid, thin metal wires, and CRO. The document describes an experiment to measure and analyze the magnetic properties of various materials by tracing their B-H hysteresis loops using a universal B-H curve tracer. This document is an instruction manual for a Universal B-H Curve Tracer instrument. Define magnetic induction (B). 3. txt) or read online for free. The goal of the database is to aid in the selection of Holmarc’s B-H curve experiment model no: HO-ED-EM-09 is used for the analysis of the magnetic hysteresis loop / B-H curve for soft iron & laminated iron cores used in two coils bound electromagnet with DC current supply. The test is normally performed by the magnet manufacturer during the initial stage of processing. The curve traces out a loop as H goes through a complete cycle, reaching saturation at high values and retaining some residual magnetism even when H is This experiment belongs to Basics of Physics-II Lab IITK. Hysteresis is the dependence of a system not only on its current environment but also on its past environment. Step 4: Using Current slider, varying the current through the solenoid and corresponding magnetic field is to be noted from Gauss meter. CURVE BOARD Aim: - To trace the hysteresis curve of a transformer core using a CRO and find the energy loss per unit volume per cycle and Jan 26, 2023 · Electronics Tutorial about Magnetic Hysteresis, Electromagnetism and the Hysteresis Loop of magnetic Materials known as the B-H Curve OBJECTIVE Study of the hysteresis curves of transformer stampings, ferrites and other magnetic materials of different shapes and determination of their energy losses. The intensity of magnetization M does not become zero when the magnetizing field H is reduced to zero.