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單項選擇題

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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單項選擇題

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

單項選擇題

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