论文部分内容阅读
高中物理是基础性学科,近来笔者发现,在各类高考复习模拟题甚至高考试卷中,常常出现了涉及大学普通物理学的问题。例如,静电场中,高中只介绍点电荷的电场强度与匀强电场的电场强度的计算公式,而没有介绍比较复杂的宏观带电体周围电场强度的计算问题。面对复杂而冗长的表达式,考生不仅感到非常陌生,甚至望而生畏,笔者便称之为“冷僻问题”。通过分析与总结发现,要判断这种“冷僻”而复杂的物理量表达式是否正确合理,显然用高中阶段的知识是不可能推导出来的。诚然,即使能推导,方法也不可取!要准确而快速解决这种“冷僻问题”唯一的方法就是,利用“单位制”(中学没有涉及“量纲”知识)和“极限思维”来“单位检验”和“合理外推”判断其正确性或合理性。
High school physics is a basic discipline, the author recently found that in all kinds of entrance exam review questions or college entrance examination papers, there are often problems involving ordinary physics in the university. For example, in the electrostatic field, high school only introduces the formula of electric field strength of point charge and electric field strength of uniform electric field, but does not introduce the calculation of the electric field intensity around the more complicated macroscopic charged body. The face of complex and lengthy expressions, candidates not only feel very strange, even dauntless, I call it “cold problems.” Through the analysis and conclusion, it is obviously impossible to deduce the knowledge of senior high school from the judgment of whether the “cold” and complex physical quantity expression is correct or not. Admittedly, the method is not advisable even if it can be deduced. The only way to accurately and quickly solve this “uncommon problem” is to use the “unit system” (secondary school does not cover “dimension” knowledge) and “Limit thinking” to “unit test ” and “reasonable extrapolation ” to determine its correctness or rationality.