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在初中物理“透镜成像作图法”的教学中,要求学生会用三条特殊光线作光路图。如果把这要求仅仅看成是一种法则来让学生掌握而不重视作图法的原理(即作图法的依据)的教学,在很多具体问题上将遇到一些很难克服的困难。例如,眼球、照相机、望远镜等物体的长度一般的都远超过透镜的孔径。如图1所示,学生将无法作出A点的像。学生也常常要问,在主光轴上的物点如何用作图法求像的位置。要解决这类问题,必须让学生学会对既不平行于主光轴又不通过主焦点的光线(如图1中的AK)如何作穿过透镜后的光路图。通常采用的“焦平面辅助法”,要引入副光轴、副焦点和焦平面等概念,必然相应
In junior high school physical “lens imaging mapping method” teaching, require students to use three special light path map. If this requirement is to be seen as merely a law that allows students to master rather than emphasize the teaching of the principle of cartography (that is, the basis of cartography), there will be some difficult problems to overcome on many specific issues. For example, objects such as eyeballs, cameras, binoculars, etc., generally have lengths that far exceed the aperture of the lens. As shown in Figure 1, students will not be able to make an image of Point A. Students also often ask how the object point on the main optical axis is used as the location of the figure's image. To solve these problems, students must learn how to make the optical path of the light that passes through the lens to the light that is neither parallel to the main optical axis nor the main focus (AK in Figure 1). The commonly used “focal plane auxiliary method”, to introduce the concept of deputy optical axis, sub-focus and focal plane, inevitable corresponding