液体表面张力系数测定仪器的改进及对测量精密度的影响

The Improved Accessory of Joly Balance and Its Effect in Measuring Liquid Surface Tension Coefficient

摘要: 目的：探讨在焦利氏秤系统上增加主尺升降控制手轮减速装置提高实验操作精密度的可行性与实现方法.方法：设计对接于立杆升降控制手轮的减速装置，内径匹配手轮外径，外径10 cm，在手部移动距离相同的情况下，主尺升降高度由原来的3 mm ± 0.1 mm降到了1 mm ± 0.05 mm，和旋钮控制载物平台下降的速率匹配程度大大提高。分别让3名熟练操作的学生和3名没有做过该实验的学生分别在无和有减速装置的情况下按标准程序常规操作，测量纯净水的表面张力系数，并计算均方根表示的精密度，利用统计软件对数据间有无显著性差异进行0.05水平效度检验。结果：精密度由原来的1.48和2.32分别提高到了0.88和1.14 (均为mN/m)，使用主尺升降控制齿轮减速辅助装置前后在0.05效度水平结果具有显著差异。结论：利用该减速装置使得实验仪器的操作更符合人体工学，增加了稳定性，减小了操作的偶然误差，提高了实验的精密度。

Abstract: Purpose: To study the method of improving measuring precision of the liquid surface tension coefficient by using an additional device on traditional Joly balance. Materials & Methods: A speed slowing-down accessory with outside diameter 10 cm was designed to match the speed of the stage by moving the inner pole from 3 mm ± 0.1 mm to 1 mm ± 0.05 mm at equal hand moving distance. The surface tension coefficient of pure water is measured before and after assembled with the speed slowing-down accessory by 3 skilled students and 3 new students respectively and the data precision of every group is calculated. The results are dealt with statistical test to show the difference. Results: The precisions have both significant differences before and after using our speed slowing-down accessory for two groups. Conclusion: Operating with our speed slowing-down device can significantly increase operating stability, decrease data error and improve precision of the experimental data.