在RLC串联电路中,求电流瞬时表达式.视在功率,有功功率,无功功率以及功率因数

R = 100 X = XL - XC = 20 - 10 = 10
Z = （R*R+X*X）^0.5 = 100.5 tana = X/R = 0.1 a = 5.7度
Im = Um / Z =200 / 100.5 = 1.99 Φ = 30 - 5.7 = 24.3 度
电流瞬时表达式；i = ImSIN(100T+Φ) = 1.99SIN(100T+24.3度)
视在功率:S = U * I =( 200/√2) * ( 1.99/√2) = 199 Kva
有功功率:P = I*I*R = ( 1.99/√2) *( 1.99/√2) *100 = 198 W
无功功率:Q= I*I*X = ( 1.99/√2) *( 1.99/√2) *10 = 19.8 Var
功率因数:cosa = cos5.7 = 0.995