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單項(xiàng)選擇題

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

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單項(xiàng)選擇題

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

單項(xiàng)選擇題

The Wheat-stone bridge is a precision measuring instrument utilizing the principle of changes in（）.

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