在R-L-C串联电路中,已知,R=80Ω XL=160Ω XC=100Ω,总电压是311sin314

u = Um sin wt = 311sin314t：
U =Um / √2= 220 V
Zx = XL - XC =60 Ω
Z = √(Zx^2+R^2) = 100 Ω
I = U / Z =2.2 A
COS Q = R / Z = 0.8
SIN Q = Zx / Z = 0.6
S = U * I = 484 VA
P = S * COS Q = 387.2 W
Q = S * SIN Q = 290.4 Var