法拉第电磁感应定律定量分析探究演示仪

针对传统的法拉第电磁感应定律演示装置只能进行定性或半定量分析的问题,设计了法拉第电磁感应定律定量分析探究演示仪,该实验装置不但能更好的演示法拉第电磁感应定律,而且还可完成定量分析和探究,演示效果好,定量分析精确度高,值得在中学物理教学中推广.     

对阿基米德定律演示仪器的改进

改进了阿基米德定律演示实验装置。通过重新设计阿基米德定律演示实验仪的支架结构和溢水杯的出水口,使整套设备操作使用方便,效果明显提高。     

电磁感应定律演示实验的改进

电磁感应定律演示实验的改进高俊发（辽宁省林业学校，沈阳１１０１０１）在电磁感应定律教学中，多数教师采用示教电流表和固定式多匝线圈，手握磁铁来定性演示电磁感应定律．我用大型光点检流计取代示教电流表，配用自制装置定量地演示了电磁感应定律，收到了满意的教学...     

利用刚体转动惯量实验仪验证转动定律的设计

介绍了设计性实验“利用刚体转动惯量实验仪验证转动定律”.该实验要求学生理解刚体动力学原理;利用实验室现有的仪器,对刚体转动惯量实验仪进行改装;提出新的实验原理,可以对阻力矩进行估测,利用该实验装置验证刚体定轴转动定律.     

研究牛顿第二定律的演示实验装置的改进

究牛顿第二定律的实验是新版全日制普通高级中学教科书(试验修订本·必修)第一册的一个重要演示实验.通过随堂演示,探索了加速度与力和质量的关系,学生看后一目了然,不失为一个好实验.它把抽象的物理原理寓于简单的实验之中,达到了事半功倍的效果.笔者在授课过程中演示了该实验,感觉要是能稍稍改进一下,其效果将会更好.现把自己肤浅的想法介绍给大家.     

利用计算机和传感器探究牛顿第二定律

牛顿第二定律是联系力学与运动学的桥梁,是中学物理的核心内容之一.探究牛顿第二定律的实验是中学教学的重要演示实验.但是传统实验中实验原理的不完善使实验存在较大的系统误差,长期以来一直是困扰中学物理教师的一个难题.     

牛顿第二定律演示实验装置的改进

介绍了用电磁铁控制小车启动、用细尼龙丝线控制其制动的演示牛顿第二定律的实验装置。     

一个取代气垫导轨验证牛顿第一定律的演示实验

牛顿第一运动定律在教材中没有安排演示实验,而通常的演示大多是在气垫导轨上进行.我们设计该演示实验不仅可以取代气垫导轨,而且取材容易,操作简单,可见度大,还可在任意方向上演示第一定律,克服了在气垫导轨上演示的固有缺点.具体介绍如下.     

阿基米德定律演示实验的改进

阿基米德定律演示实验的改进吕振国（吉林柳河柳南乡通沟中学，１３５３２１）阿基米德定律演示实验的教学可做如下改进，效果很好．装置如图所示．图中ａ、ｂ分别为两个弹簧，可用５００ｇ弹簧秤上的弹簧，在左侧各有一个标尺；ｃ是物体，最好选用２５０ｃｍ３的塑料瓶装...     

法拉第电磁感应定律定量实验的创新

本装置结合现代技术利用Arduino与电子元器件等定量验证法拉第电磁感应定律,探究感应电动势与磁通量变化率、角速度、匝数等因素的关系,有助于教师教学演示及学生理解,激发学生对科技与物理的学习兴趣.     

Beyond Snel's law: Refraction of a nano-beam of light

The refraction of a localized narrow beam is significantly different from that of a plane wave. As the beam width decreases to be in the order of the wavelength, the refraction behavior deviates noticeably from Snel's law, and when the width of a light beam is smaller than about one fifth of the wavelength of the incident light, finite-difference time-domain simulations demonstrate that refraction becomes negligible. That is, the narrow light beam retains its propagation direction even after entering another medium at an oblique angle. The result reveals novel features of nano-beams and may have applications in precise biomedical measurement or micro optical device.     

Maxwell’s demon and the second law of thermodynamics

An idealized, two-dimensional Maxwell demon is described which incorporates an irreversible process. The vertex of the device acts as a purely mechanical ‘trap door’. This idealized mechanism is found to generate a violation of the second law of thermodynamics. These results indicate that the second law of thermodynamics is not valid in general for idealized, irreversible systems.     

微波光学组合实验中大角度入射时反射波波强极大方向的确定

利用PASCO微波光学组合实验装置,分析了微波大角度反射偏离反射定律的原因,给出了可视为大角度入射时的最小入射角,定量地计算了大角度入射时微波反射波极大时的反射角.     

焦耳定律实验的改进

针对教材中关于焦耳定律的实验中的不足,对该实验做了相应的改进,将教材中的吸热物质煤油改为空气,通过空气的受热膨胀来演示焦耳定律,实验现象较为明显,并且改进后的装置,液面升高的情况能同时展现在学生面前,对比性较好.     

Mixture steering law design for control moment gyroscopes

Focusing on the singularities of a spacecraft using control moment gyros(CMGs)to do the large angle maneuvers,a new mixture steering law is proposed to avoid the singularities.According to this method,if the CMGs are far away from the singularity,the Moore-Penrose pseudo-inverse steering law(MP)is used directly.If the CMGs are close to the singularity,instead of solving the inverse matrix,a set of optimal gimbal angles are sought for the singular measurement to reach the maximum,which can avoid the singularities.Simulations show that the designed steering law enables the spacecraft to carry out the large angle maneuver and avoid the singularities simultaneously.     

绝对零度与可溶性物质质量密度的等压膨胀法测量

对盖吕萨克实验装置进行改进,用水柱代替水银柱,采用等压膨胀法既能验证了盖吕萨克定律,又可测得绝对零度与可溶性物质的质量密度.     

Is There an Optimal Substrate Geometry for Wetting?

Within a 1+1-dimensional SOS type model with a periodic rough substrate, we show that the differential wall tension, which governs wetting, has a maximum as a function of a certain aspect ratio of the substrate. This result is based on a low-temperature expansion leading, in a first approximation, to Wenzel's law for the wall tension and allowing us to study the corrections to this law. It implies that the contact angle is minimum for a substrate with the corresponding aspect ratio. Our results are in agreement and explain recent numerical simulations.     

利用DISLab定量探究焦耳定律

针对新、旧人教版高中物理教材均缺少对焦耳定律实验探究的问题,利用DISLab设计相应实验内容,并自制配套的实验装置,实验过程操作简单,数据图像清晰明了,实现了对焦耳定律的科学定量探究.     

Optimal guidance law design for impact with terminal angle of attack constraint

According to the requirements of the precision guidance of air-to-surface weapons with multiple constraints, a new optimal guidance law applying to attack the ground stationary target is designed. On the basis of dividing the 3D movement of the weapon into the movements of diving plane and turning plane, the relative motion of weapon-target is established first. Considering the conditions of miss distance, impact angle and terminal angle of attack, the general formulation of a new guidance law with an arbitrary system order is deduced by solving the Riccati equation of the quadratic optimal control. The approximate expressions of lag free system and first-order lag system are given. The validity of the optimal guidance law is verified by the comparable simulations of the characteristic trajectory. The simulation results shows that the optimal guidance laws satisfy the precision guidance with impact angle constraint as well as the angle of attack converges to zero at final time, which is important for warhead effect.     

伏安法测电阻如何减少测量误差的分析

伏安法测电阻有误差,如何减少误差方法很多,本文采取还原法即还原电流法和还原电压法,以消除电流表的分压,电压表的分流,达到减少误差的目的。