用板式电位差计测电池的电动势和内阻的实验研究

给出了用板式电位差计测电池电动势和内阻的原理与方法,分析了如何选取电路中的电池E、标准电阻Rs和限流电阻R的取值,使实验效果最佳。运用最小二乘法处理实验数据,实验结果令人满意。     

电位差计测干电池内阻实验的设计与分析

通过分析电位差计测量干电池内阻实验的设计方法,使实验能达到更有利的测量条件和更准确的测量结果。     

电位差计测干电池内阻实验中异常值问题的探讨

通过测量干电池内阻随放电电流的变化关系,分析电位差计测量干电池内阻过程中出现异常值的原因并指出克服的办法。     

用板式电位差计测干电池内阻时附加的标准电阻取值大小分析

分析标准电阻取值大小对测量可能产生的影响。若标准电阻取值太大,测量线路的灵敏度将降低,同时标准电阻真实值相对额定值的差异对测量结果的影响也变大;若标准电阻取值太小,流过干电池的电流变大,干电池内部极化会使干电池内阻增大。实测结果也支持上述分析。     

用自组电位差计测干电池电动势和内阻

用自组电位差计测干电池电动势和内阻于文华（东北师大物理系长春１３００２４）在设计性实验中，我们开设了“用自组电位差计测干电池电动势和内阻”的题目．很受学生们欢迎，收到了预期的效果．其实在选作这个实验题目之前，学生们已经作了用箱型电位差计测电池电动势及...     

用板式电位差计测干电池内阻时附加的标准电阻取值大小分析简

分析标准电阻取值大小对测量可能产生的影响。若标准电阻取值太大，测量线路的灵敏度将降低，同时标准电阻真实值相对额定值的差异对测量结果的影响也变大；若标准电阻取值太小，流过于电池的电流变大，于电池内部极化会使干电池内阻增大。实测结果也支持上述分析。     

箱式电位差计测干电池电动势的误差分析

用电位差计测电源电动势是大学物理实验中一个典型的电学实验,由于运用到了补偿法测量原理使测电动势的精确度提高．电位差计不仅可以用来精确测量电源电动势,还可用来测量电流、电阻等等,由于其在工程领域里的广泛应用,电们差计实验是工科学生在大学中常做的大学物理实验之一．     

用电位差计测电流表内阻

本文提出几种利用电位差计测电流表内阻的方法和计算不确定度的公式，引做了实验验证和综合评述。     

对十一线电位差计测电动势值的讨论

补偿法是电磁测量的一种基本方法，电位差计就是利用补偿法来精确测量电动势或电位差的仪器．它有多种类型，其中十一线电位差计是一种教学仪器，它结构简单、直观性强，便于学习掌握，电位差计不仅可以测量电动势或电位差，与标准电阻配合还可以测量电阻和电流，有些电器仪表厂则用它来确定产品的准确度和定标．但在使用时，由于各种配件，特别是配件滑动变阻器的构造及应用的局限性，应该使测量值的位数是唯一的三位有效数。     

用板式电势差计测量电池的电动势和内阻实验的改进

分析了在“用板式电势差计测量电池的电动势和内阻”实验中 ,由于待测干电池的电动势和内阻在实验过程中均不为恒定值而引起的误差 ,依据电化学理论和电阻构成解释了实验现象 ,并给出了实验改进方案 .     

板式电势差计测量电动势及内阻实验的改进

通过对原板式电势差计测量电池电动势及内阻实验的分析，得出 Rs-R关系图，从而求出电动势和内阻。     

二极管伏安特性曲线测试电路的改进

指出了文献中所给出的伏安法测二级管特性曲线电路存在的问题，并给出了改进电路。     

Construction and calibration of a multipurpose instrument to simultaneously measure dose,voltage and half-value layer in X-ray emission equipment

This work reports on the development of a multipurpose instrument that simultaneously measures delivered dose (air kerma), peak voltage (kVp) and half value layer (HVL) in X-ray machines. The device will help control quality of X-ray equipment routinely used in diagnostic and interventional radiological procedures. The measuring device is equipped with several attenuating filters of different materials and thicknesses, and Gafchromic^® XR-QA2 radiochromic films are used as sensitive elements. The films are scanned after being irradiated and the resulting color intensities indicate a relationship between the degree of film darkening under each individual filter and the quantities of interest, i.e. air kerma, kVp and HVL. Comparing HVL values measured using the proposed multipurpose instrument with those of a reference standard ionization chamber, discrepancy reached 8.4%. As for the kVp evaluation, anomalous results were observed for low atomic number materials and small thicknesses, especially for peak voltages higher than 70 kVp. However, for materials with higher Z and reasonable thickness, the calibration curve R × kVp was quite satisfactory, being R the ratio between the color intensities obtained with two distinct filters. We have also observed a decrease in the influence of Tungsten characteristic radiation on the calibration curve. These results suggest that the proposed instrument may be satisfactorily used to routinely control quality of X-ray equipment, estimating the radiation dose resulting from the direct beam, the applied voltage across the electrodes and the half value layer.     

Comparative investigation of the resistance and ability to trigger high voltage discharge for single and multiple femtosecond filaments in air

A comparative investigation of the resistance and ability to trigger high voltage(HV) discharge for a single filament(SF) and multiple filaments(MFs) has been carried out.The experimental results show that the trend of the breakdown threshold of the SF exactly follows that of its resistance,but this is not the case for the MF.The MF’s resistance is much smaller than the SF’s.However,the MF shows a slightly higher HV breakdown threshold than the SF.The underlying physics is that the measured resistance of the MF is collectively contributed by every filament in the MF while the HV breakdown threshold is determined by only one single discharging path.     

A new model analysis of the third harmonic voltage in inductive measurement for critical current density of superconducting films

The critical current density J c is one of the most important parameters of high temperature superconducting films in superconducting applications,such as superconducting filter and superconducting Josephson devices.This paper presents a new model to describe inhomogeneous current distribution throughout the thickness of superconducting films applying magnetic field by solving the differential equation derived from Maxwell equation and the second London equation.Using this model,it accurately calculates the inductive third-harmonic voltage when the film applying magnetic field with the inductive measurement for J c.The theoretic curve is consistent with the experimental results about measuring superconducting film,especially when the third-harmonic voltage just exceeds zero.The J c value of superconducting films determined by the inductive method is also compared with results measured by four-probe transport method.The agreements between inductive method and transport method are very good.     

Possibility of persistent voltage observation in a system of asymmetric superconducting rings

The possibility of observing persistent voltage in superconducting rings of different arm widths is experimentally investigated. It was previously found that switching of the arms between superconducting and normal states by an AC current induces DC voltage oscillation in the magnetic field with a period corresponding to the flux quantum inside the ring. We used systems with a large number of asymmetric rings connected in series to investigate the possibility of observing this quantum phenomenon near the superconducting transition, where thermal fluctuations lead to switching of ring segments without an external influence and the persistent current is much smaller than in the superconducting state.     

Comparative investigation of resistance and ability to trigger high voltage discharge for single and multiple femtosecond filaments in air

A comparative investigation of resistance and ability to trigger high voltage (HV) discharge for single filament (SF) and multiple filaments (MF) has been carried out. The experimental results show that the trend of the breakdown threshold of the SF exactly follows that of its resistance, but this is not the case for the MF. The MF's resistance is much smaller than SF's. However, the MF shows a bit higher HV breakdown threshold than the SF. The underlying physics is that the measured resistance of the MF is collectively contributed by every filament in the MF while the HV breakdown threshold is determined by only one single discharging path.     

由阴、阳极电压及入射光强及频率确定光电流

根据费米-狄拉克统计,本文推导出了一个光电效应中光电流作为阴、阳极电压的函数关系.应用本文所提供的函数所得计算结果同实验结果非常好地符合.其次,建立了入射光强对光电流贡献的数学表现,最后,从数学上得到了入射光频率与光电流的关系,从而能够预测光电流.