通常我们期望学生通过透镜实验能推论出在眼睛背面所成的象是倒立的象.但还有另一种简便方法能更直接地演示这一结果.在一块卡片上戳一个较大的针孔。站在窗子旁边,闭上一只眼睛,把卡片放在离另一只眼睛约20cm 处。通过针孔看远处的天。针孔将呈现为一块模糊的斑。(注意:现在眼睛是聚焦在无穷远处,下面还要继续保持这 Often, we expect students to deduce through lens experiments that the image formed on the back of the eye is an inverted image, but there is another convenient way to demonstrate this more directly: Poke a larger pinhole on a card . Stand by the window, close one eye and place the card about 20 cm from the other eye. See the distant days through the pinhole. The pinhole will appear as a blurry spot. (Note: Now the eyes are focused on infinity, the following should continue to maintain this