本题目来源于试卷: Electrostatic Force and Electric Field，类别为 美国物理杯赛(Physics Bowl)
[单选题]
94.39: A small object zyit3 zsgz b(k 6p mte8vs,h*0t8q8c7 with charge q and we x vlqp lau, l7o)5l6usc1q4a7ight mg is attached to one end of a string of length L. The other end is attached to a stationary support. The system is placed in a uniform horizontal electric field E, as shown in the accompanying figure. In the presence of the field, the string makes a constant angle q with the ve ua5ol) ps4quc xla17 qlv7 6,lrtical. What is the sign and magnitude of q?
A. positive with magnitude mg/E
B. positive with magnitude mg tanθ/E
C. negative with magnitude mg/E
D. negative with magnitude mg tanθ /E
E. negative with magnitude E tanθ /mg
参考答案: B
本题详细解析:
暂无
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