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已知u=220sin(314t-120°)V,i1=2sin(314t+60°)A,i2=3sin(314t+150°)A,i3=4sin(314t-45°)A。在保持相位差不变的条件下,将电压u的初相位改为0°,则下列表达式正确的是()。
A.i1=2sin(314t-150°)A
B.i2=3sin(314t-90°)A
C.13=4sin(314t+75°)A
D.i2=3sin(314t-30°)A
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A.i1=2sin(314t-150°)A
B.i2=3sin(314t-90°)A
C.13=4sin(314t+75°)A
D.i2=3sin(314t-30°)A
A.通过用电器R0的电流的有效值是20 A
B.升压变压器的输入功率为4650 W
C.发电机中的交变电流的频率为100 Hz
D.当用电器的电阻R0减小时,发电机的输出功率减小
A.220sin(50t+30O),220sin(50t+30O)
B.380sin(50t+60O),220sin(50t+30O)
C.220sin(50t+30O),380sin(50t+60O)
D.380sin(50t+60O),380sin(50t+60O)
电压和电流的瞬时值表达式分别为u=220sin(ωt-10°)和i=5sin(ωt-40°),那么()。
A.电流滞后电压40°
B.电流滞后电压30°
C.电压超前电流50°
D.电压超前电流30°