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
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相关考题
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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 -
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
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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
