在电阻丝上测量薄透镜的焦距

MEASUREMENT OF THE FOCAL LENGTH OF A THIN LENS BY RESISTANCE THREAD

本文提供了一种用电学原理在一根电阻丝上测量薄透镜焦距的实验方法。该方法利用均匀电阻丝的电阻与其长度成正比的关系,把长度量转换成电阻量进行测量,并通过标定,可以在一块数字电压表上直接显示待测薄透镜的焦距值。如果薄透镜的焦距已知,利用该方法也可以确定薄透镜所成清晰像的位置。实验结果的相对不确定度小于3%。

This paper proposes an experimental method to measure the focal length of a thin lens by using a resistance thread according to electricity principle. In considering that the resistance of a uniform thread is proportional to its length, the length quantity can be converted to resistance quantity in measuring. By calibrating procedures the value of the focal length of a thin lens can be displayed immediately on the screen of a digital vohmeter. In case we know the focal length,we may determine the position where a clear image may be observed. The relative uncertainty of the experimental results may be controlled within 3%.