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一、理解的误区题目:如果加在某定值电阻两端的电压由U_1变到 U_2(设 U_2>U_1),通过该电阻的电流变化了ΔI,则该电阻消耗的功率变化了多少?本题常以数字出现于各地的中考题中,在我所教的学生中,很多学生对此题的解法是这样的:P=UI(?)ΔP=ΔUΔI=(U_2-U_1)ΔI…①但①式的答案却是错误的,而学生却不易观察出来.我们可以用下述思路来进行理解:设定值电阻阻值为 R,当 R 两端的电压由
First, the misunderstanding of the subject: If the voltage across a fixed-value resistor changes from U_1 to U_2 (set U_2>U_1), the current through the resistor changes by ΔI, how much power is consumed by the resistor? Numbers appear in the examination questions in various places. Among the students I teach, many students solve this problem in the following way: P=UI(?)?P=?U?I=(U_2-U_1)?I...1 but 1 The answer is wrong, but the student is not easy to observe. We can use the following ideas to understand: The setpoint resistance is R, when the voltage across R is