谁都有这样的经验:物体太小或者太远,眼睛就无法辨认它的细节,有时甚至什么也看不到,例如细菌谁也看不到它;物体变化太快,同样也看不清它的变化过程,例如,用肉眼只能看到电光闪闪,无法观察到放电的各个发展阶段。为什么会产生这种现象呢? 原来,肉眼一般来说只能分辨视角不小于1分的两个点。如果它们的视角小于1分,那么肉眼就分辨不出来是两点,而是看成一点。例如,在地面上可以分辨50米处 Everyone has the experience that if the object is too small or too far away, the eye cannot discern its details, and sometimes even nothing can be seen. For example, no one can see it; the object changes too quickly and it cannot be seen clearly. The process of change, for example, can only be seen with the naked eye, and can not observe the various stages of development of the discharge. Why does this phenomenon occur? It turned out that in general, the naked eye can only distinguish two points with a viewing angle of not less than 1 point. If their perspective is less than 1 point, then the naked eye can not distinguish two points, but as a little. For example, 50 meters can be distinguished on the ground