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这是2013年河北中考物理试卷中的一道压轴题。题目如下:如图1所示L上标有“6V 3W字样,电流表量程为0~0.6A,电压表量程为0~15V,变阻器R的最大电阻为100Ω。只闭合S1,滑片置于a点时,变阻器连入电路中的电阻为Ra,电流表示数为Ia,只闭合S2,移动滑片,变阻器两端电压与其连入电路的电阻关系如图2所示;当滑片置于b点时,电压表示数Ub=8V,电流表示数为Ib。已知Ra:Ro=12:5,Ia:Ib=3:5。(灯丝电阻不随温度变化)求:(1)小灯泡的电阻;(2)定值电阻Ro和电源电压;(3)在电表的示数不超过量程,灯泡两端的电压不超过额定值的情况下,只闭合S1时,变阻器连入电路的最小电阻为多少;只闭合S2时,电路消耗的最小功
This is the 2013 senior high school entrance examination physics papers in a finale. The topics are as follows: As shown in Figure 1 L marked ”6V 3W words, ammeter range of 0 ~ 0.6A, voltmeter range of 0 ~ 15V, rheostat R maximum resistance of 100Ω only closed S1, the slider placed a point, the rheostat connected into the circuit resistance Ra, the current that the number of Ia, only closed S2, moving the vane, rheostat voltage across the circuit connected to its resistance as shown in Figure 2; when the vane is placed b point, the voltage that the number of Ub = 8V, the current that the number of Ib. Known Ra: Ro = 12: 5, Ia: Ib = 3: 5 (filament resistance does not change with temperature) Resistance; (2) the value of resistance Ro and power supply voltage; (3) the meter does not exceed the range, the voltage across the bulb does not exceed the rated value of the case, only closed S1, the varistor connected to the circuit of the minimum resistance How many; only closed S2, the minimum power consumption circuit