单项选择题Voltage generated by most AC generators is fed from the machine to the bus by means of().

A.brushes on a commutator
B.brushes on slip rings
C.slip rings on a commutator
D.direct connections from the stator


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1.单项选择题Electrical leads and insulation on a motor should be painted with().

A.heat-resisting acrylic
B.heat-resisting aluminum
C.insulating varnish
D.insulating white lead

2.单项选择题The electrolyte in a lead-acid storage battery consists of distilled water and ().

A.hydrogen chloride
B.calcium chloride
C.sulfuric acid
D.muriatic acid

3.单项选择题A circuit breaker and a fuse have a basic similarity in that they both ().

A.can be reset to energize the circuit
B.should open the circuit when overloaded
C.will burn out when an over current flow develops
D.All of the above

5.单项选择题The frequency output of an operating alternator is controlled by the ().

A.relative speed of the rotor poles
B.number of turns of wire in the armature coil
C.strength of the magnets used
D.output voltage

6.单项选择题The greatest detrimental effect on idle electrical equipment, such as cargo pump motors, is the().

A.loss of residual magnetism
B.absorption of moisture in the insulation
C.insulation varnish flaking
D.dirt collecting on the windings

7.单项选择题The Wheat-stone bridge is a precision measuring instrument utilizing the principle of changes in().

A.inductance
B.capacitance
C.resistance
D.amperage

9.单项选择题One factor that determines the frequency of an alternator is the().

A.number of turns of wire in the armature coil
B.number of magnetic poles
C.strength of the magnets used
D.output voltage

10.单项选择题The device that most commonly utilizes the principle of electromagnetic induction is the().

A.diode
B.transformer
C.transistor
D.rheostat