在分析凸透镜成像时,常见这样的问题:物体放在凸透镜前成实像,若将凸透镜遮住一半,观察实像有何变化?答案是像的位置、大小都不改变,只是比原先的暗了,即亮度减小。这个答案有问题。应分两种情况讨论。在没有光屏承接实像的情况下,我们直接 In the analysis of convex lens imaging, a common problem is that the object is placed in front of the convex lens. If the convex lens is half hidden, how does the observation of the real image change? The answer is that the position and size of the image do not change, but are darker than the original. That is, the brightness decreases. There is a problem with this answer. It should be discussed in two situations. In the absence of light screens to accept real images, we directly