《E物质的磁性》PPT课件.ppt
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1、Chapter 10 Magnetism of matter1 Magnetic medium and its classification2 Magnetization Magnetic field intensity 3 Ferromagnetic substance4 Example1 Magnetic medium and its classification1 1 Magnetic medium (1)Magnetic mediumMagnetic medium 磁介质(2)在磁场作用下发生变化,并能反过来影响磁场的物质(2)The Magnetization of magnetic
2、 mediummagnetic medium:磁介质的磁磁介质的磁化化磁介质在磁场作用下的变化称为磁化2 The classification of magnetic mediumRelative permeability 相对磁导率In medium:各种物质都具有一定的磁性,都能对磁场产生影响,因此一切物质都可以认为是磁介质。(2)Paramagnetic medium 顺磁质 manganese、chrome、oxygen etc.The B in medium is larger than in vacuum.(3)Ferromagnetic medium 铁磁质 iron、cobal
3、t、nickel etc.The B in medium is more lareger than in vacuum.(1)Diamagnetic medium 抗磁质(2)copper、plumbum、hydrogen etc.The B in medium is less than in vacuum.Typically r differs from unity by only a few parts in 1052 Magnetization 磁化强度磁化强度 Magnetic field intensity 磁场强度磁场强度1 The Magnetization of magneti
4、c mediumThe motion of electron spin:电子自旋运动:电子自旋运动:spin magnetic moment自旋磁矩自旋磁矩;The motion of electron orbit:电子绕核运动:电子绕核运动:orbit magnetic moment 轨道磁矩;轨道磁矩;Molecular magnetic moment分子磁矩分子磁矩,固有磁矩:固有磁矩:所有电子的轨道磁矩和自旋磁矩的矢量和。所有电子的轨道磁矩和自旋磁矩的矢量和。Molecular current:分子电流分子磁矩用等效的圆电流表示。(1)Molecular magnetic moment
5、 分子磁矩分子磁矩(2)Additional magnetic moment 附加磁矩附加磁矩In an external magnetic induction,the every electron of molecule experiences force which is called Lorentz force.Lorentz force.电子的运动状态发生改变。这时,每个电子的运动,除了自旋运动和绕核运动之外,还要附加一个以外磁场为轴线的转动,称为电子的进动 the precessional motion of electron.无外磁场时,分子磁矩的排列杂乱无章;In an exte
6、rnal magnetic induction,molecular magnetic moment experiences torques It shows that the magnetic moment tends to orient itself parallel to the field分子磁矩沿外磁场方向排列-顺磁性 paramagnetism 其方向总是与外磁场相反抗磁性 diamagnetism 用电磁感应现象可以说明附加磁矩方向与外磁场方向相反:If the flux through a circuit changes,an electromotive force is ind
7、uced around it.The polarity of the induced emf is such as to oppose the change that caused it.The induced current always flows to create a magnetic field that opposite the change in flux through the circuit.Using the Lorentz Lorentz force of electron experienced the diamagnetism can be explained too
8、:根据电子受力方向判断电子进动形成的电流流向,从而确定对应的附加磁矩的方向The motion of electron forms additional magnetic moment电子的进动,形成附加磁矩2 Magnetization and Magnetization current单位体积内分子磁矩或附加磁矩的矢量和。表征介质的磁化程度Paramagnetic medium:分子磁矩起主要作用Diamagnetic medium:附加磁矩起作用(1)Magnetization (2)Magnetization current 磁化电流磁化电流由于磁化而在磁介质的边缘形成的环形电流Lon
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