单项选择题
The power factor is a measure of the phase difference between voltage and current and is expressed as the（） of the phase angle.
A.sine
B.cosine
C.tangent
D.cotangent
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相关考题
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单项选择题
With a purely resistance load the voltage and current are in phase, giving a power factor of （）.
A.one
B.less than one
C.more than one
D.negative one -
单项选择题
The alternating current generator supplying a load has a voltage drop resulted from the loadWhen the load has a lagging power factor this voltage drop （）.
A.is small
B.may be neglected
C.is useful
D.is considerable -
单项选择题
After the trouble of the automatic control system has been completely eliminated, assistance is （） required.
A.remained
B.still
C.no longer
D.much mere
