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题目:已知一盏电灯直接接上电源时的功率是100瓦。若将此电源接上一段长导线后,再接上这盏电灯,导线上所消耗的功率为9瓦。此时,电灯的实际功率是多少?(设灯丝电阻不变) 这个题目,乍一看感到无从下手。如深入分析,灵活运用相关知识,不仅可解,而且还有多种解法。 解法1:根据两种情况下电源电压不变列方程。 电灯直接接电源时,电源电压U=(P_1R_灯)~(1/2)。接上长导线时,电路中的电流I_2=(P_2/R_灯)(1/2),电路中的总功率
Title: It is known that when a lamp is directly connected to a power source, the power is 100 watts. If you connect this power supply to a long wire, and then connect it to the lamp, the power consumed on the wire is 9 watts. At this point, what is the actual power of the lamp? (Assuming that the resistance of the filament does not change) This question, at first glance, seems impossible to start with. Such as in-depth analysis, flexible use of relevant knowledge, not only solvable, but also a variety of solutions. Solution 1: According to two cases, the power supply voltage is not the same as the column equation. When the lamp is directly connected to the power supply, the power supply voltage U = (P_1R_lamp) ~ (1/2). When the long wire is connected, the current in the circuit I_2=(P_2/R_lamp)(1/2), the total power in the circuit