有一正弦交流电压,表达式为u=311sin(314t–四分之拍)V求该交流电压的角频率,频率,有效值,最大值和初相位,

ω = 314 rad/s
f = ω / 2π = 50 Hz
U = Um / √2 = 311 / √2 = 220 V
Um = 311 V
φ = - 45°
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