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 undej ;vz geraz0/+.i dln.rlies the operation of essentially all electric motorsgazr n /.v j+z;el0id.4uk 1;jyutnt *ki/c3t?1/t ukt *tn4ucj;k3iy
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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