图1是滑动变阻器在电路中的两种常见连接方法,滑动头P移动时使其两边电路的电阻同时改变,引起干路和支路的电阻、电流等物理量起复杂的变化,有些物理量的变化是非单调性的。此类问题对分析推理能力及运用数学处理物理问题的能力要求较高。下面拟先分析两个电路的等效电阻再讨论含此电路的一类典型题的解法。 Fig. 1 shows two common connection methods of the sliding rheostat in the circuit. When the sliding head P moves, the resistance of both sides of the circuit changes simultaneously, which causes complex changes in physical quantities such as resistance and current of the trunk and branch, and changes in some physical quantities. It is non-monotonic. Such problems require higher ability to analyze reasoning and to use mathematics to deal with physical problems. The following is to analyze the equivalent resistance of the two circuits first and then discuss the solution of a class of typical problems with this circuit.