




版权说明:本文档由用户提供并上传,收益归属内容提供方,若内容存在侵权,请进行举报或认领
文档简介
1、Chapter 35 Magnetic Properties of Materials1Chapter 35 Magnetic Properties of MaterialsChapter 35 Magnetic Properties of Materials235-1 The Magnetic Dipole 1. DefinitionAi loop theofmoment dipole magnetic Thedirection and magnitude of 30303202322202 22 )( )(2zBiAzzRiRzzRiRBMagnetic dipole produces m
2、agnetic field.Chapter 35 Magnetic Properties of Materials3 The effect of magnetic field on the magnetic dipole momentB)(EpmaxstableunstableChapter 35 Magnetic Properties of Materials4Interacting energy of magnetic dipole in magnetic field If U=0, when = /2, then . BU2/dsindsinddiBAWiBAW)(EpU)cos(cos
3、 )d(cos 2iBAiABcos)()( 2BUUcos)(BUWhen = 0, U is minimum.Chapter 35 Magnetic Properties of Materials5 2. The field of a dipoleA bar magnet can be considered to be a magnetic dipole.Chapter 35 Magnetic Properties of Materials635-2 The Force on a Dipole in a Nonuniform fieldzBBzzUFBUzzzzzdd)(dddd12122
4、1Permanent dipoles are attracted to the source of the field.Permanent magnetic dipole momentsChapter 35 Magnetic Properties of Materials7 In summary, in a nonuniform magnetic field, permanent dipoles are rotated into alignment with the field and attached to the source of the field, but induced dipol
5、es are repelled from the source of the field.Induced magnetic dipole momentsInduced dipoles are repelled from the source of the field.Chapter 35 Magnetic Properties of Materials835-3 Atomic and Nuclear Magnetism 1. Orbital magnetic dipole momentAtomic dipole tiny current looprereeefTei22)2(vvlmel2B
6、is Bohr magneton lmemmerrmll22 ,vvBlnhnmehnl22 ,2 if222vverrreiAChapter 35 Magnetic Properties of Materials9 2. Intrinsic magnetic moment (spin moment)Smes2 The total magnetic moment of an atom is obtained from the vector sum of the orbital and spin magnetic moments of all its electrons.Chapter 35 M
7、agnetic Properties of Materials10 3. Nuclear magnetism The nucleus has a magnetic moment with two parts: orbital magnetic moment of protons and intrinsic magnetic moment of protons and neutrons. 4. Nuclear magnetic resonanceBUsSmes2Nobel prize in physics 1952:Bloch & Purcell for their developmen
8、t of new methods for nuclear magnetic precision methods and discoveries of connection therewith.Chapter 35 Magnetic Properties of Materials11NMRIChapter 35 Magnetic Properties of Materials12Paul C.Lauterbur USPeter Mansfield UK The Nobel prize in physiology or medicine for their discoveries concerni
9、ng magnetic resonance imaging. (2003)Chapter 35 Magnetic Properties of Materials1335-4 Magnetization(a) In an unmagnetized sample:(b) In an magnetized sample:Define the magnetization M:VVMnThere are three field: applied magnetic field B0, magnetized field BM, net magnetic field B.MBBB0Chapter 35 Mag
10、netic Properties of Materials14a long solenoid of circular cross section with a magnetic materialMBBMBM000 0BBm)1(0EEe)(0m00) 1(material. theofty permeabili is BMmmChapter 35 Magnetic Properties of Materials15Magnetization of materials surface current Chapter 35 Magnetic Properties of Materials16nIB
11、nlIlBsB00000 dMMnInIBIInlBlsB000 )(dMmmmnInInInIBB00000 ,Magnetic Material and Amperes LawAmperes law for a solenoid:magnetic material is inserted,IM is surface current. Chapter 35 Magnetic Properties of Materials17Amperes law should be amended as: d0IsBm) 1(mMII d0IsBm ) , , d(00HHBBHIsHmmChapter 3
12、5 Magnetic Properties of Materials1835-5 Magnetic Materials 1. Paramagnetism The atoms of this material have permanent magnetic dipole moments. B0 and 0M are parallel, B B0.Curies law: when B0/T is smallTBCM0Adiabatic demagnetization to decrease the temperature of system.Chapter 35 Magnetic Properti
13、es of Materials19 2. Diamagnetism Such materials might be those having atomic magnetic dipole moments of zero. B0 and 0M are antiparallel, B 1, B B0.m is not a constant.Chapter 35 Magnetic Properties of Materials21magnetic domains B=0 B B B BChapter 35 Magnetic Properties of Materials22Hysteresis an
14、d magnetic domainsPoint c: remains magnetized even when the applied field B0 is zero.Point d: a saturated magnetization in the opposite direction.Point e: retains a permanent magnetization.Point b: a saturated magnetization in the original direction.Ferromagnetism can “remember” how it became magnet
15、ized.BChapter 35 Magnetic Properties of Materials23fPoint f: Hf Coercive forcePoint c, e: Bc Remanent magnetizationsoft magnetic material BChapter 35 Magnetic Properties of Materials24hard magnetic material moment magnetic material Chapter 35 Magnetic Properties of Materials25Chapter 35 Magnetic Pro
16、perties of Materials26Quick quiz What happens when a paramagnetic substance is placed in an external magnetic field?(1). The atomic dipole moments weaken slightly, but tend to line up with the external field.(2). The atomic dipole moments strengthen slightly, and tend to line up with the external fi
17、eld.(3). The atomic dipole moments weaken slightly, and tend to line up against the external field.(4). The atomic dipole moments strengthen slightly, but tend to line up against the external field.Chapter 35 Magnetic Properties of Materials27 Quick quiz Three curves a, b, and c show the magnetizing process of paramagnetic, diamagnetic and ferromagnetic substance respectively. The dashed line denoted relationship B-H in vacuum. Which curve is represent diamagnetic substance?(1). a(2). b(3). cChapter 35 Magnetic Propertie
温馨提示
- 1. 本站所有资源如无特殊说明,都需要本地电脑安装OFFICE2007和PDF阅读器。图纸软件为CAD,CAXA,PROE,UG,SolidWorks等.压缩文件请下载最新的WinRAR软件解压。
- 2. 本站的文档不包含任何第三方提供的附件图纸等,如果需要附件,请联系上传者。文件的所有权益归上传用户所有。
- 3. 本站RAR压缩包中若带图纸,网页内容里面会有图纸预览,若没有图纸预览就没有图纸。
- 4. 未经权益所有人同意不得将文件中的内容挪作商业或盈利用途。
- 5. 人人文库网仅提供信息存储空间,仅对用户上传内容的表现方式做保护处理,对用户上传分享的文档内容本身不做任何修改或编辑,并不能对任何下载内容负责。
- 6. 下载文件中如有侵权或不适当内容,请与我们联系,我们立即纠正。
- 7. 本站不保证下载资源的准确性、安全性和完整性, 同时也不承担用户因使用这些下载资源对自己和他人造成任何形式的伤害或损失。
最新文档
- 材料质量培训效果评估支持合同
- 餐饮企业员工劳动合同签订与备案指南
- 产业链上下游循环额度融资合同范例
- 餐饮品牌拓展店铺面房屋租赁及培训合同
- 老人和儿童教学课件
- 大学反诈考试试题及答案
- 美术课件介绍作家
- 美术欣赏儿童课件图片
- 安全月度例会总结
- 安全生产报告 sitegovcn
- 无固定期限劳工合同通知书
- GB/T 45161-2024液氢容器用安全阀技术规范
- 《中医推拿按摩教程》课件
- 煤炭采购及运输的合规性流程
- 2025年浙江杭州市上城区人力资源开发服务有限公司招聘笔试参考题库附带答案详解
- 供电所所长讲安全课
- 浙江省宁波市九校2023-2024学年高一上学期1月期末联考数学试题(解析版)
- 小红书种草营销师(初级)认证考试真题试题库(含答案)
- 梅尼埃病的中医治疗
- 战略合作框架协议
- 药品经营使用和质量监督管理办法2024年宣贯培训课件
评论
0/150
提交评论