单选题 When the voltage remains constant and the resistance is increased in a series circuit, the flow of current______.

A、 increases by the square of the original value

B、 increases

C、 remains the same

D、 decreases

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相关试题

单选题 What device is used to parallel two alternators nowadays?

A、A pointer

B、Two windings

C、A synchroscope

D、Two synchronizing lamps

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单选题 When the load has a lagging power factor this voltage drop is considerable. This sentence means that ______.

A、with a purely resistance load, the voltage drops too much

B、there is a considerable voltage drop in the capacitive load combined with resistance load

C、when the load is the capacitive load combined with resistance load, the voltage drops to zero

D、when the load is the inductive load combined with resistance load, the voltage drop is fairly large

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单选题 In practice, the paralleling switch is closed as the synchroscope pointer reaches the 11 o'clock position while it is moving______ .

A、in the FAST section

B、in the SLOW section

C、towards the FAST direction

D、towards the SLOW direction

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单选题 Which of the following statements is TRUE according to the passage?

A、With a purely resistance load, the power factor is zero.

B、Inductive loads combined with resistance loads produce leading power factors.

C、Capacitive loads combined with resistance loads produce lagging power factors.

D、With a purely resistance load, the phase angle is zero.

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单选题 The underlined word "machines" in the passage refers to ______

A、the direct current generator

B、the alternating current generator

C、the exciter

D、the prime mover

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单选题 The correct moment for synchronizing is when______

A、three lamps are equally bright

B、three lamps darken in rotation

C、the key lamp is bright and the other two lamps are dark

D、the key lamp is dark and the other two lamps are equally bright

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单选题 The exciter must vary with ______ ①load current; ②the power factor; ③speed change of the prime mover

A、only ①

B、only ②

C、① and ②

D、①, ② and ③

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单选题 When two alternators are said to be "in phase",______

A、their current outputs are changing

B、their voltages are changing at the same rate

C、they are connected one to each side of the paralleling switch

D、they have the same maximum voltage

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