不少资料上有如下一题:如图1所示,电源电动势为E,图1图2内阻不计,电阻R0上的电压为U=2E,滑动变阻器上消耗的功率为P,将电源与电阻R0交换位置后(滑动触头不动),如图2所示,则交换位置后:(A)R0上的电压仍为U.(B)R0上的电压小于U.(C)滑动变阻器上的功率一定大于P.(D)滑动变阻器上的 A lot of data has the following question: As shown in Figure 1, the power EMF is E, the internal resistance of Figure 1 is not counted, the voltage on resistor R0 is U=2E, the power consumed on the sliding rheostat is P, and the power supply is After the resistor R0 switches position (sliding contact does not move), as shown in Figure 2, after the exchange position: (A) The voltage on R0 is still U. (B) The voltage on R0 is less than U. (C) Sliding rheostat The power on the must be greater than P. (D) on the sliding varistor