本题目来源于试卷: Physics Unit20: Magnetism，类别为 通用国际物理
[单选题]
What fundamental fact undet+kdruln . 6c4zq w1v*rli cfjt4+q)-xaz:e6 hgu :c/ml ies the operation of essentially all electric motorsiejxc:u6 +)tmql/gcfz4a: -h ?
A. Opposite electric charges attract and like charges repel.
B. A current-carrying conductor placed perpendicular to a magnetic field will experience a force.
C. Alternating current and direct current are both capable of doing work.
D. Iron is the only element that is magnetic.
E. A magnetic north pole carries a positive electric charge, and a magnetic south pole carries a negative electric charge.
参考答案: B
本题详细解析:
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