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在讲点电荷的电场时,我让学生思考这样一个问题:在以点电荷为球心的球面上,任意两点的场强是否相等?学生讨论后形成了两种截然不同的观点,一种观点认为:任意两点的场强不相等,因为场强是矢量,矢量相等必须要大小、方向均相同,而它们的方向不同;另一种观点则认为:任意两点的场强是相等的,虽然它们方向不同,但相等是一个数量关系,是指场强的大小.更让我惊奇的是:这两种观点的支持率几乎各占50%.在另一个班教学时,我把问题改为:在以
When I talk about a charged electric field, I ask students to think about the question: Is the field strength at any two points equal on the sphere with point charge as the center of the ball? After the discussion of the students, there are two very different views. The point of view is that the field strength at any two points is not equal, because the field strength is a vector. Vectors must be the same size and direction, and their directions are different. Another view is that the field strength at any two points is equal. Although they are in different directions, the equality is a quantitative relationship and refers to the size of the field strength. What makes me even more amazed is that the support rate for these two viewpoints is almost 50% each. When teaching in another class, I put the question Change to: In order to