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1 引言在用物距像距法测量凸透镜的焦距实验中,从理论上讲在不同的物距范围内,下述两种调节方法均易从像屏上得到清晰像:(1)物和透镜固定(令物距大于焦距),调节像屏成像;(2)物和像屏固定(令二者间距满足成实像的条件),调节透镜成像。但实际情况并非如此,实验中发现,当物距在某一范围内时,调节透镜较调节像屏易得到清晰像(即调节透镜过程中,像屏上像的清晰度变化明显,容易确定像的准确位置),而在其他物距范围内调节像屏又较调节透镜容易得到清晰像。两种调节方式的区别是:第一种情形,像静止不动,像与像屏之间相对位置的变化量也就是手调节像屏产生的变化量;第二种情形,调节透镜时物距要发生变化,像的位置
1 INTRODUCTION In the experiment of measuring the focal length of a convex lens by the object distance image method, theoretically speaking, in the range of different object distances, the following two adjustment methods are easy to get clear images from the image screen: (1) object and lens Fix (make the object distance greater than the focal length), adjust the imaging screen image; (2) Fix the image and the screen (make the distance between the two meet the condition of real image), adjust the lens imaging. However, the actual situation is not the case. Experiments have found that when the object distance is within a certain range, the adjusting lens is easier to be clearly imaged than the adjusting screen (ie, the sharpness of the image on the screen during the adjustment of the lens changes significantly, and it is easy to determine the image. The exact position of the image is easily adjusted by adjusting the lens in other object distances. The difference between the two adjustment methods is as follows: in the first case, such as standing still, the amount of change in the relative position between the image and the image screen is the amount of change in the hand to adjust the image screen; in the second case, the object distance when adjusting the lens To change, like the position