定性演示刚体绕定轴转动时角动量守恒

定性演示刚体绕定轴转动时角动量守恒张双明，陈荣福（天津理工学院）在一般普物教科书中，验证刚体绕定轴转动时角动量守恒，一般采用人持哑铃站或坐在转凳上，通过展臂、收臂演示转动时角动量守恒规律Ｉω＝恒量，我们认为，这一实验不仅装置沉重、不便携带，而更主要的...     

角动量演示仪器的设计

设计了角动量演示装置 ,该装置结构简单 ,便于携带 ,可较好的演示角动量守恒和决定转动惯量的因素等 .     

一种可自动改变力矩方向的课堂角动量定理演示实验

给出了高速自转陀螺在连续周期性外力矩作用及力矩突变下的运动规律演示,实现了力矩可自动改变方向的角动量运动规律演示实验,还给出了在理论上角动量n次变化率不为零的一种实例演示．     

轨道角动量指向可控的紧聚焦时空波包(特邀)EI北大核心CSCD

利用Debye积分,研究了三个相互正交的轨道角动量(包括两个正交的横向轨道角动量以及一个纵向轨道角动量)光场在紧聚焦条件下的复杂耦合现象,并演示了焦场中相位奇点在三维时空间中的演化。此外,还研究了具有不同拓扑荷数的纵向轨道角动量对聚焦波包整体轨道角动量指向的影响。数值结果表明,聚焦波包的整体轨道角动量指向可由纵向轨道角动量的拓扑荷数进行调控,进而实现紧聚焦时空波包的轨道角动量指向可控。这种角动量指向可控的时空波包在光学微操作、微纳加工、自旋-轨道耦合以及量子通信等领域具有潜在的应用价值。     

角动量守恒的简单演示

角动量守恒的简单演示冯法军（承德石油专科学校０６７０００）做好角动量守恒定律的演示，对讲清概念，理解规律，能起到事半功倍的效果．本文介绍一个筒便宜行、明自易懂的演示方法．制做一根稍长的圆木棒，半径２ｃｍ左右，长１米左右．加工或找一个质量在２０ｇ左右的...     

一种多功能的角动量定理演示仪

介绍了一种用于课堂的多功能角动量定理演示仪,结构简单,操作方便,能演示出多种角动量定理相关实验,揭示刚体定点转动中深刻的物理规律,并采用在"自然坐标系"下的角动量定理对实验现象加以理论分析.     

电磁学与电动力学中的磁单极-I

本文及后继三篇文章在电磁学和电动力学框架内分别介绍磁单极的若干奇特性质.针对由一个磁单极和一个点电荷构成的体系,首先证明这个体系的电磁场角动量具有极简洁的表达式并讨论可能的电荷量子化,然后显式地演示体系角动量的转化与守恒.     

自制角动量守恒演示仪

利用微型平面推力球轴承和简易的旋转装置,代替茹科夫斯基转椅,能方便地定性演示角动量守恒规律.     

物理演示的组合实验与综合实验

一、组合演示实验按实验内容物理演示可分为单一性、组合性和综合性实验．大多数情况下，为了配合一个物理现象、概念或定律的讲解而演示一个实验，这就是单一性演示实验．对于某些内容，则可安排或设计一组实验，这些实验的题目和目的相同，内容相互补充，逐渐深化，对于建立正确的物理概念或图像、普遍性地验证物理定律、培养学生科学的思维方法，将收到比单一实验好得多的效果．我们把这一组实验称为组合演示实验．例如，验证角动量守恒定律有很多现成的仪器和实验，其中大家所熟知的离心节速器式角动量守恒演示仪只能演示不受外力矩作用…     

利用流体演示角动量守恒

利用流体在转动状态下连续流失，使得系统的转动惯量变小，从而导致角速度增大，较为直观地演示角动量守恒原理．     

Transfer of angular momentum to matter from acoustical vortices in free space

An experimental demonstration of the mechanical transfer of orbital angular momentum to matter from acoustical vortices in free field is presented. Vortices with topological charges l=+/-1 and l=+/-2 were generated and a torsion pendulum was used to study the angular momentum transfer to hanging disks of several sizes. This allowed us to make a comparative study of the effective acoustical torque in terms of topological charge of the vortex, the disk radius, and its position along the main propagation axis. A theoretical discussion of the generated sound fields is also provided.     

Intrinsic and extrinsic nature of the orbital angular momentum of a light beam

We explain that, unlike the spin angular momentum of a light beam which is always intrinsic, the orbital angular momentum may be either extrinsic or intrinsic. Numerical calculations of both spin and orbital angular momentum are confirmed by means of experiments with particles trapped off axis in optical tweezers, where the size of the particle means it interacts with only a fraction of the beam profile. Orbital angular momentum is intrinsic only when the interaction with matter is about an axis where there is no net transverse momentum.     

Momentum,angular momentum,and equations of motion for test bodies in space-time with torsion

The definitions and transformation properties of momentum and angular momentum of test bodies possessing both macroscopic rotation and net spin are discussed. The equations of motion for momentum and angular momentum of test bodies are derived and written in a covariant form when the energy-momentum tensor is symmetric.     

单光子轨道角动量的传输特性研究

描述了高阶椭圆厄米-高斯光束及其单光子平均轨道角动量,并分析了一些与其单光子轨道角动量变化的有关情况,通过计算机仿真简要进行了说明.最后分析了单光子轨道角动量在空间某范围的概率分布及其变化情况.研究结果表明,高阶椭圆厄米-高斯光束与物质相互作用时,其单光子平均轨道角动量的变化幅度随接触物质材料的不同而异.     

Chaos bound in Kerr-Newman-Taub-NUT black holes via circular motions

In this study, we investigate the influence of the angular momentum of a charged particle around Kerr-Newman-Taub-NUT black holes on the Lyapunov exponent and find spatial regions where the chaos bound is violated. The exponent is obtained by solving the determination of the eigenvalues of a Jacobian matrix in the phase space. Equilibrium positions are obtained by fixing the charge-to-mass ratio of the particle and changing its angular momentum. For certain values of the black holes' electric charge, the NUT charge and rotational parameter, a small angular momentum of the particle, even with zero angular momentum, causes violation of the bound. This violation disappears at a certain distance from the event horizon of the non-extremal Kerr-Newman-Taub-NUT black hole when the angular momentum increases to a certain value. When the black hole is extremal, the violation always exists no matter how the angular momentum changes. The ranges of the angular momentum and spatial regions for the violation are found. The black holes and particle rotating in the same and opposite directions are discussed.     

Canonical momentum,angular momentum,and helicity of circularly polarized Airy beams

We report a study of the momentum, angular momentum, and helicity of circularly polarized Airy beams propagating in free space. By using the vector angular spectrum representation, the explicit analytical expressions for the electric and magnetic field components of circularly polarized Airy beams are derived in detail. To overcome the drawbacks of classical kinematics formulae when applied to structured light beams, a general canonical approach is introduced to describe the momentum, angular momentum and helicity of Airy beams. Numerical simulation results for the spatial distributions of the canonical momentum, spin and orbital angular momentum, as well as the helicity densities are presented and discussed. This study may provide useful insights into the dynamical properties of Airy beams that may be important in several applications, including the optical control, micromanipulation, and information processing.     

Four-wave mixing of light beams with engineered orbital angular momentum in cold cesium atoms

We report an experimental demonstration that shows that the spatial structure carried by engineered coherent superpositions of light beams with orbital angular momentum can be mapped into the nonlinear polarization induced in a cloud of cold cesium atoms. The structure of such polarization was revealed by nearly degenerate four-wave-mixing processes.     

Anomalous angular momentum in the presence of a vortex

The angular momentum of a charged boson in the presence of a vortex is calculated using collective coordinates in the two-dimensional, abelian Higgs model. In agreement with already published assertions, angular momentum is found to be half-integer when the vortex flux is quantized in half-integer units.