单选题 1分

A direct current passing through a wire coiled around a soft iron core is the description of a simpl...

A direct current passing through a wire coiled around a soft iron core is the description of a simple ____.
  • A. magnetic shield (磁性屏蔽)
  • B. electromagnet (电磁铁)
  • C. piezoelectric (压电的) device
  • D. electromagnetic domain (电磁范围)

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1 单选题 1分
  • A. the number of conductors in series per winding
  • B. the speed at which the magnetic field passes across the winding
  • C. the strength of the magnetic field
  • D. all of the above
2 单选题 1分
  • A. brushes on a commutator
  • B. brushes on slip rings
  • C. slip rings on a commutator
  • D. direct connections from the stator
3 单选题 1分
  • A. The generator need not excitation.
  • B. There are three phase winding on the rotor
  • C. The winding on the rotor is for inputting excitation current
  • D. The generator has brushes
4 单选题 1分
  • A. Armature and equalizer
  • B. Commutator and brushes
  • C. Rotor and interpoles
  • D. Field and exciter
5 单选题 1分
  • A. neutralize armature reaction
  • B. conduct electric current to an outside circuit
  • C. convert DC current to AC current
  • D. provide excitation to a DC generator