Friday, April 10, 2015

white sr maxwell assumption of homogeneity (no preferred origin) and isotropic (no preferred direction) of space

路径依赖
right now, assume both 乙肝,丙肝 are treatable, then it is not 路径依赖;

if 丙肝 is not treatable, and you get it, then your life, luck are all  路径依赖: you get 乙肝, you are ok; you get 丙肝, you are done this life.


热统计物理学,时间有方向,路径依赖,初试点或条件很重要,生死攸关

but there is this theoretical argument, that if we make


旋转变换_百度百科

baike.baidu.com/view/2028050.htm 轉為繁體網頁
简称旋转。欧氏几何中的一种重要变换.即在欧氏平面上(欧氏空间中),让每一点P绕一固定点(固定轴线)旋转一个定角,变成另一点P′,如此产生的变换称为平面上( ...
缺少字詞: isotropic
  • chap07邻域运算_百度文库

    wenku.baidu.com/view/101a3f8583d049649b665809 轉為繁體網頁
    2010年11月2日 - ... 和,拉普拉斯算子可以简化为: 有几种不同的模板计算形式: Laplacian算子也是各向同性(isotropic)的,考虑坐标旋转变换,设旋转前坐标为,旋转 ...
  • Laplace算子的旋转不变性的证明| NARUTOACM

    www.narutoacm.com/archives/laplace-rotation-invariant/ 轉為繁體網頁
    2013年1月1日 - 所谓算子可看成一种变换,作用在函数上,生成另一个函数。 ... 好的滤波器模版应当是各向同性的(isotropic),即具有旋转不变性(rotation invariant)。
  • https://www.physicsforums.com/search/632980/

    am going to give an answer that's probably more difficult than necessary. Classicaly, two frames are inertial if observer in each frame can agree on Newton's Laws (law of inertia, f=ma, action/reaction). Turns out that they must be moving at constant speed relative to each other. If you are in an accelerated frame, then newton's laws won't hold. The first one, for example, would break down, because object would have acceleration without force (there is an ambient force due to the fact that the observer is accelerating). The problem is how do we jump from one frame to another so that measurements in each frame agree. By simple assumption of homogeneity (no preferred origin) and isotropic (no preferred direction) of space one can prove that there are three kinds of transformation possible: one with a speed minimum, one with a speed maximum (Lorentz), and one with neither (Galileon). The first kind turns out to violate causality. And the third kinds turns out to be invalid because some other law of physics is not invariant under it (Maxwell's Eqn). So one conclude that the second one to be correct and the third one to be a limiting case of it (limit as the speed limit goes to infinity). And for all law (included EM) to be correct, this speed limit must be the speed at which EM disturbance travel in vaccum, i.e. the speed of light. Arriving at this conclusion requires 5 assumptions: 1) all Law of physics is invariant when you go from one inertial frame to another. 2) the transformation from one frame to another is linear 3) spacetime is homogeneous 4) spacetime is isotropic 5) Causality is preserved. I like this derivation better because the speed limit turn out to be a result, not an assumption. And the 5 assumptions above are more "obvious", "trivial", and "intuitive". In short, inertial frame are frames that moves at constant speed with respect to each other. And by assuming the 5 assumptions above, and using some group theory and linear algebra. One arrive at the Lorentz transformation which has stand the tests of experiments

    Reference https://www.physicsforums.com/threads/what-is-an-inertial-reference-frame.11148/

    Maxwell's equations - Wikipedia, the free encyclopedia

    en.wikipedia.org/wiki/Maxwell's_equations
    Wikipedia
    Loading...
    For the history of the equations, see History of Maxwell's equations. ..... For homogeneous materials, ε and μ are constant throughout the material, while for ... For isotropic materials, ε and μ are scalars, while for anisotropic materials (e.g. due to ...
  • [PDF]EM Waves, Wave Propagation in Linear/Homogeneous ...

    web.hep.uiuc.edu/home/serrede/P436/Lecture.../P436_Lect_06.pdf
    o μ = magnetic permeability of free space = 4π × 10. −7. Henrys/m. Thus, Maxwell's equations for theE and B fields inside this linear, homogeneous and isotropic.
  • [PDF]Chapter 1 Electromagnetic Theory ² Maxwell's Equation

    www.colorado.edu/...fa05/Chapter1.pdf
    University of Colorado Boulder
    Loading...
    The electromagnetic theory of optics begins with Maxwell's equation. ..... We have seen how plane wave propagate in vacuum or in isotropic homogeneous.
  • [PDF]Lesson 9 - NICADD

    nicadd.niu.edu/~piot/phys_630/Lesson9.pdf
    medium then Maxwell's equations simplify to. • For now on we consider non-magnetic media (M=0) and ... Linear, homogeneous, isotropy, nondispersive media.
  • [PDF]Electromagnetic Waves in Homogeneous Media - MIT

    web.mit.edu/.../Lec02_Waves-v11....
    Massachusetts Institute of Technology
    Loading...
    therefore solution is any function with identical dependencies on space and time (up to a constant). Maxwell's Equations in linear isotropic homogeneous ...



  • 如图所示,坐标空间中有场强为E的匀强电场和磁感应强度为B的匀强磁场,y轴为两种场的分界面,图中虚线为...如图所示,坐标空间中有场强为E的匀强电场和磁感应强度为B的匀强磁场,y轴为两种场的分界面,图中虚线为磁场区域的右边界.现有一质量为m,电荷量为-q的带电粒子从电场中坐标位置(-L,0)处,以初速度v0沿x轴正方向开始运动,且已知L=
    m
    v
    2
    0
    qE

    试求:要使带电粒子能穿越磁场区域而不再返回电场中,磁场的宽度d应满足的条件.


    答案:解:带电粒子在电场中做类平抛运动,设粒子进入磁场时的速度大小为v,速度方向与y轴的夹角为θ,如图所示,则:
    vy=
    qE
    m
    ?
    L
    v0
    =v0
    题库巴巴

    v=
    v
    2
    0
    +
    v
    2
    y
    =
    2
    v0

    cosθ=
    vy
    v
    =
    2
    2
    ,θ=45°;
    粒子在磁场中做匀速圆周运动的半径为:R=
    mv
    qB

    要使带电粒子能穿越磁场区域,磁场的宽度应满足的条件为:d<(1+cosθ)R
    即:d<
    (1+
    2
    )mv0
    qB

    答:要使带电粒子能穿越磁场区域而不再返回电场中,磁场的宽度d应满足的条件为d<
    (1+
    2
    )mv0
    qB
    点评:本题考查带电粒子在匀强磁场中的运动,要掌握住半径公式、周期公式,画出粒子的运动轨迹后,几何关系就比较明显了.
    分析:粒子在电场中受到的电场力的方向向上,粒子做类平抛运动,水平方向做的是匀速运动,竖直方向做的是匀加速直线运动,从而可以求得带电粒子运动到Y轴上时的速度;当磁场的运动的轨迹恰好与磁场的右边沿相切时,此时的磁场的宽度最大,根据粒子的运动的轨迹可以求得磁场的宽度最大值.



    •   评论 & 纠错   

  • 1.如图所示,坐标空间中有场强为E的匀强电场和磁感应强度为B的匀强磁场,y轴为两种场的分界面,图中虚线为磁场区域的右边界.现有一质量为.....
  • 2.如图所示,在平面坐标系xOy内,同种带正电离子,质量m=1.0×10-20kg、带电量q=1.0×10-10C,以相同速度不断从C.....
  • 3.如图所示,在xOy坐标系第一象限有垂直于纸面向外、磁感应强度为B的匀强磁场,在第四象限有垂直于纸面向里、磁感应强度也为B的匀强磁场.....
  • 4.在水平面上有一沿y轴放置的长为L=1m的细玻璃管,在管底有光滑绝缘的带正电的小球.在第一象限中存在磁感应强度为B=1T的匀强磁场,.....
  • 5.如图所示,已知正方形abcd边长为l,e是cd边的中点,abcd所围区域内是一个磁感应强度大小为B、方向垂直于纸面的匀强磁场,一带.....
  • 6.如图所示,带正电的粒子以水平速度v0从平行金属板MN间中线OO′连续射入,MN板间接有如图乙所示的随时间变化的电压uMN,令电场只.....
  • 7.一带正电q、质量为m的离子,t=0时从A点进入正交的电场和磁场并存的区域作周期性运动,图甲为其运动轨迹,图中弧AD和弧BC为半圆弧.....
  • 8.如图所示,在空间中存在垂直纸面向里的场强为B匀强磁场,其边界AB、CD的宽度为d,在左边界的Q点处有一质量为m,带电量为负q的粒子.....
  • 9.如图所示,两平行金属板E、F之间电压为U,两足够长的平行边界MN、PQ区域内,有垂直纸面向外的匀强磁场,磁感应强度为B.一质量为m.....
  • 10.如图甲所示,两平行金属板A、B的板长L=0.2m,板间距d=0.2m,两金属板间加如图乙所示的交变电压,并在两板间形成交变的匀强电.....
  • 11.如图甲所示纸平面内一群相同带电粒子,以相同速度连续从A点开始做直线运动,一段时间后进入一垂直于纸面向里的圆形匀强磁场区域(图中未画.....
  • 12.如图所示,在坐标系Oxy的第一象限中存在沿y轴正方向的匀强电场,在其余象限中存在匀强磁场,磁场方向垂直纸面向里.A是y轴上的一点,.....

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