不需估读的螺旋测微器

螺旋测微器是借助螺旋的转动，将螺旋的角位移转变为直线位移进行长度测量的一种精密仪器，是高中乃至大学物理实验的基本仪器之一，与游标卡尺一样，分两步进行读数；但比卡尺读数复杂，学生不易掌握，经常发生读数错误．一是固定套管上的整圈数容易数错，导致测量数据和真实数据相差0．5mm；二是从活动套管上读出不到一整圈的小数时，需要加1位估计数字，许多同学容易疏忽，忘记最后1位估计数字，使得测量数据少1位有效数字而导致读数错误．其中第二种错误发生频率较高．     

游标和螺旋测微器的组合应用

游标卡尺与螺旋测微器作为两种基本的测量仪器，大家一定不会陌生．二者的原理、构造虽各不相同，但它们却都达到了较为精确地测量长度这一共同目的．然而，进一步设想能否将二者的功能结合起来，在优化组合下，再一次提高它们的测量精度，这确是十分有诱惑力的．根据我校物理系学生胡建的创意及老师的提示，我开始了自己的设计与这一新产品的制作．     

选择合格天平,做好物理实验

在初中物理教学中，正确的选择、使用和维护天平是搞好有关天平教学的关键．在新教材中，天平的实验是以托盘天平为主，在选择托盘天平时大致从以下几个方面进行：一、检查天平指针能否指分度盘零刻度．一般天平横梁上的螺旋在没有调节到头以前，指针都能指分度盘的零刻度．但还是有一些天平，横梁上的螺旋已经调节到头了，指针仍然不能指分度盘的零刻度．出现这种现象时，需将天平托盘取下，拧开下面的螺丝，调节下面的配重沙粒，一直到天平指针指分度盘的零刻度为止．二、检查天平是否等臂．先将天平调节好，使指计指零刻度．再用两个相同…     

用螺旋电桥法测微小长度

以螺旋测微器为基础并加以改进,将微小长度放大并转换为电阻值,通过单臂惠斯通电桥再次放大并测量阻值,从而求得待测物体的长度。与传统螺旋测微器相比,高线性电阻和高灵敏度的惠斯通电桥的使用,使得测量精度和灵敏度有较大提高     

100 keV回旋电子束参数测量

 利用电子束轰击快响应荧光屏获得电子束横截面图像的方法，对100 keV大回旋轨道空心电子束(Cusp电子束)在横截面上的束轮廓及电荷密度分布进行了测量，计算出回旋电子束半径、螺旋角等参数，并与相同条件下的计算机数值模拟结果进行了对比和分析。测量结果表明初始磁场强度从0.003 5 T增加到0008 2 T时，电子束的拉莫半径从3.2 mm增加到3.9 mm，螺旋角从0.7增加到1.0，满足使用此电子束的回旋行波放大器的调试需求。     

基于双臂电桥的组合式测微方法

利用普通物理实验室的常见器材,如千分尺、变阻箱、检流计、电阻丝、导线等,根据螺旋放大、电桥平衡原理设计了螺旋电桥式测微仪.介绍了该装置的原理、使用方法和测量效果.     

基于菲涅耳声透镜的声速与焦距的测量实验

将"空气中声速测量"实验和"薄透镜焦距测量"实验融合,设计了集声学原理和光学原理的"菲涅耳声透镜"实验,明确了该实验所使用的实验仪器,给出了实验内容,即测量声透镜的焦距、通过测量声透镜的几何参量得出超声波的波长、测量超声波在空气中的声速.最后,制作了焦距f为50mm的声透镜,并对实验内容进行了可行性分析及实验验证.实验结果(声透镜的焦距为50.3mm及超声波波长值8.70mm)与理论设计值基本一致.     

如何准确测量这个额定功率?

如何测量额定电压为3．8V的小灯泡的额定功率呢？因为3．8V大于3V，因此不能直接用电压表0～3V的量程测量小灯泡两端的电压；但是如果实验中用电压表0～15V的量程测量小灯泡两端的电压，由于0～15V的量程的分度值是0．5V，就无法准确测量3．8V的电压，因此，这个实验并不能准确测量小灯泡的额定功率．那么能不能设法准确测量额定电压为3．8V的小灯泡的额定功率呢？     

游标卡尺、千分尺实验教学中不容忽视的细节

在大学和高职的物理实验教学中,一般都安排游标卡尺、千分尺使用的实验．虽然学生在高中已接触过这两种仪器,但在大学和高职再做这两种实验时,出现了不少细节问题．通过纠正这些看似细微的问题,可以很好地培养学生严谨的科学态度和良好的科学素养     

微型光学元件的透过波面畸变的数字化检测

介绍了由浙江大学研制的CQG II型车间数字干涉仪检测 φ3 6mm× 0 5mm平行平面玻璃的透过波面畸变的情况。最近研制出的干涉仪测量的最大口径为 φ60mm ,采用移相式条纹扫描数字化处理 ,基于WINDOWS操作系统实现实时检测 ,以优于λ/ 30的精度计算出被检件的波面误差。工厂生产检测表明 :在上述仪器上增加一个 4倍口径的放大系统 ,可以使通光口径 φ3 1mm的工件达到 42 0 0个采样点 ,仪器的透射测量标准干涉腔误差PV≤ 0 0 2 8λ ,仪器隔日多次测量重复性PV≤ 0 0 3λ。该仪器已经正常投入使用 ,生产的用于光学信息产品的微型光学件已为日本先锋公司 (PIONEER)复检通过 ,成为工厂批量生产过程质量控制 (QC)的重要手段。     

关于"太阳在银河系中所受引力与到银心距离r的关系"的讨论

讨论了银道面内的引力场强分布和太阳在银河系中所受引力与到银心距离r的关系，指出引力场强g并不是与r的平方成反比，这是由于银河系的大小和形状不能忽略造成的．强调了万有引力定律的适用条件．     

On the calculation of the bremsstrahlung in the region of the plasma frequency

On the basis of the classical theory of radiation produced in incomplete Coulomb interaction, a formula is derived for the coefficient of the bremsstrahlung of fully ionized plasma. In the region of rectilinear approximation a comparison is made with the results of the quantum formula derived from the Born approximation. Furthermore, the influence of dispersion upon the emission coefficient is taken into account; some relations for the region of dispersion are given.     

Dependence of the Intensity of the Spectral Lines and the Composition of the Sample and the Plasma Parameters of the Unipolar Arc

The investigation was made of the dependence of the intensity of Tl, Ga, Mo, Mg, Mn, Sn, Bi, Ni, Zn, Pt and Au spectral lines and the plasma parameters (temperature T, electron concentration n_e, degree of 6 ionnization α) from concentration of lithium additive.     

On the predictability of the positions of the convergence zones in the ocean

The disagreement between the experimental and calculated positions of the first convergence zone are known from many publications. The most probable cause for such a disagreement, namely, the incorrect specification of the input data for the calculations, is considered. The lack of simultaneity between the hydrological surveys of the region and the acoustic experiments is emphasized. The experimental data obtained by the author in five ocean regions are presented. These data characterize the diurnal variability of the distance from the source to the nearest boundary of the convergence zone. The relations proposed by different researchers for calculating the sound speed from the temperature, salinity, and hydrostatic pressure are analyzed. It is shown that these relations lead to a substantial difference in the estimated depth dependence of the hydrostatic gradient of the sound speed. The position of the first convergence zone is calculated for the propagation conditions determined by vertical temperature and salinity profiles with the subsequent recalculation of these profiles into sound speed profiles by using eight different formulas known from the literature. It is shown that different formulas lead to different values of the distance to the first zone; this difference is substantially greater than that between the calculations and experiment. The necessity of improving the recalculation relations in view of the experimental data on sound propagation in natural oceanic waveguides, including the data on the actual positions of the convergence zones, is emphasized.     

Extracting the wavefunction of the LSP at the LHC

We consider associated production of squarks and gluinos with the lightest supersymmetric particle (LSP), or states nearly degenerate in mass with it. Though sub-dominant to pair production of color SU(3)-charged superpartners, these processes are directly sensitive to the wavefunction composition of the lightest neutralinos. Exploiting event-shape variables - including some introduced here for the first time - we are able to identify the composition of the LSP by selecting events involving a single high-pT jet recoiling against missing transverse energy. We illustrate the proposed technique on a set of benchmark cases and propose methods for applying these results in more realistic experimental environments.     

Set the controls for the heart of the Sun

In this paper we describe experiments conducted with high-power lasers that are attempting to replicate, for a very short time and in miniature, conditions found in the Sun. Experiments to date have reached conditions in the outer part of the Sun. To reach the Sun's centre requires compression of material to very much greater than solid density and heating to over ten million degrees. To achieve this, a new class of experiments and a new generation of high-power lasers are required.     

On the Question of the Source of the Apokamp

Technical Physics - The object of this work is the apokamp—a new type of plasma jet, which is formed from a bright offshoot emerging at the bending point of a channel of a high-voltage...