物体经透镜成像时 ,用光屏接收与用眼睛直接观察的结果常常是不同的 ,但这种差别往往会被忽视 ,这可能造成学生认识上的误解 .现举例说明 ,以期引起广大同仁重视 .在现行高中物理课本 (实验本 )中有这样一道题 :在如图 1所示的成像情况中 ,如果把凸透镜的下半部用遮光板挡住 , When an object is imaged by a lens, the results of receiving with a light screen and directly observing with the eye are often different, but this difference is often overlooked, which may cause students to misunderstand the understanding. Now illustrate, in order to arouse the attention of the majority of my colleagues. In the current high school physics textbook (experimental), there is such a problem: In the imaging situation shown in Fig. 1, if the lower half of the convex lens is blocked by a shading plate,