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在初中物理教学过程(特别是初三教学)中,常会碰到同一电路的两种状态,并要求根据前后两种状态的各个电学量之间的相互关系,求出其它的量。如下例: 例1 如图1所示,电源电压保持不变,变阻器滑片在a端和b端时,灯泡的功率之比为4:1,当滑片在a端时,电灯正常发光,电流表读数为1.5A。当滑片滑到b端时电压表读数为12V,求灯泡的额定电压和额定功率。
In the junior high school physics teaching process (especially the third grade teaching), it often encounters two states of the same circuit, and requires that the other quantities be determined based on the relationship between the respective electrical quantities of the two states. The following example: Example 1 As shown in Figure 1, the power supply voltage remains the same, when the varistor slider is at the a-end and the b-end, the ratio of the power of the light bulb is 4:1. When the slide is at the a-end, the light is normally lit. The ammeter reads 1.5A. When the slide slides to end b, the voltmeter reads 12V. Find the rated voltage and power rating of the lamp.