本题目来源于试卷: Electricity and Circuits: Internal Resistance，类别为 美国物理杯赛(Physics Bowl)
[单选题]
12.39: For the circuit shown, hrbtr4ew8a). 1 7ncln i.d,afall wire ac/: xcb oxm4o9k a)chb ,.sw9n(gd(js have no resistance, the battery has a const (9os n9/xk:ca w4c c)jbdxhoag,mb. (ant internal resistance of $r = 8.0Ω$ and the two lightbulbs (#1 and #2) are identical, each with resistance R bulb. The variable resistor is initially setto $R = 26.0Ω$ . The switch in the circuit now is closed. To what resistance must the variable resistor be set if bulb #1 is to have the same brightness after the switch is closed as it did with the switch open?
A. $9.0Ω$
B. $13.0Ω$
C. $16.0Ω$
D. $22.0Ω$
E. The answer can be computed only if the bulbs’ resistance$R_bulb$ is known.
参考答案: A
本题详细解析:
暂无
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