单项选择题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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1.单项选择题The power factor of an AC generator operating singularly is determined by the ()

A.connected load
B.prime mover speed
C.field excitation
D.generators rated voltage

2.单项选择题The resistance of electric wire will decrease as its ()

A.length increases
B.cross-sectional area increases
C.temperature increases
D.percent of metallic purities increases

3.单项选择题The total power consumed in a parallel circuit is ()

A.the sum of the powers used in each load (resistor)
B.divided by the number of loads
C.always less than the power used in the smallest load
D.the sum of the powers used in each individual load never more than the power used in the largest load

4.单项选择题Current measuring instruments must always be connected in ()

A.series with a circuit
B.parallel with a circuit
C.series-parallel with a circuit
D.delta with the shunt

5.单项选择题The primary function of an electric motor is to ()

A.develop torque
B.generate high voltages
C.produce a magnetic field
D.generate high electrical resistance

6.单项选择题The power factor at which a paralleled AC generator operates is usually adjusted by the ().

A.connected load
B.prime mover speed
C.field excitation
D.generators rated voltage

8.单项选择题Equal power factors on paralleled AC generators are maintained by an automatic ().

A.voltage regulator
B.reverse power relay
C.reverse current relay
D.governor control switch

9.单项选择题To equalize the power factor of two alternators operating in parallel, the ()

A.field excitation of both units is adjusted
B.governors of both units are adjusted
C.phase sequence is altered
D.kilowatt load is evenly divided

10.单项选择题An advantage of DC motors over AC motors is that they ()

A.are less expensive
B.require less maintenance
C.can be started across the line
D.offer a more effective means of controlling speed