“动态电路”问题既是初中电学学习中的难点,同时也是中考的热点.此类问题主要是由开关的断开、闭合或滑动变阻器滑片的移动引起的:一是通过开关的断开、闭合,改变电路的连接方式,从而引起电路中电阻变化,用电器两端的电压和电路中电流也随之发生改变;二是通过滑动变阻器滑片的移动改变电路中的电阻,从而引起电路中的电流和用电器两端电压 The problem of “dynamic circuit ” is not only the difficulty of junior high school electrical learning, but also the hot spot of senior high school entrance examination.These problems are mainly caused by the disconnection, closing or sliding rheostat vane’s movement of switch: firstly, , Closed, changing the connection of the circuit, causing the resistance change in the circuit, with the voltage across the electrical circuit and the current in the circuit also changes; the second is through the sliding rheostat vane movement changes in the circuit resistance, causing the circuit The current and voltage across the appliance