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有些学生由于不能灵活地应用已学过的数学知识,对于较复杂或较综合的物理题目,虽然能列出几个方程,但总认为方程个数少于未知量个数,因而到头来还是束手无策,解不出正确答案。诚然,从数学角度来说,独立方程的个数要等于未知量个数,未知量才能全部解出。但物理毕竟不等于数学,在解答物理习题时,如果只需求出所有未知量中的其中一个或几个,那么即使独立方程个数少于未知量个数,也可以运用解题技巧求出需求的量。兹举两例说明如下。例1.如图1所示,ε_2=4V,ε_3=6V,当开关K与1相连时,伏特表的读数为4V;当开关K与2相连时,伏特表的读数为1.6V。求K与3相连时伏特表的读数(电
Some students cannot apply the learned mathematics knowledge flexibly. Although they can list several equations for more complex or more comprehensive physical problems, they always think that the number of equations is less than the number of unknowns. Can’t solve the correct answer. It is true that, from a mathematical point of view, the number of independent equations is equal to the number of unknowns, and the unknowns can all be solved. But physics, after all, is not equal to mathematics. If you only need to find one or more of all the unknowns in solving physical problems, then even if the number of independent equations is less than the number of unknowns, you can use the problem-solving skills to find the requirements. The amount. Two examples are given below. Example 1. As shown in Figure 1, ε_2 = 4V, ε_3 = 6V. When the switch K is connected to 1, the voltmeter reading is 4V; when the switch K is connected to 2, the voltmeter reading is 1.6V. Find the reading of the voltmeter when K is connected to 3 (electricity