A.u=380sin(100t+180°)V
B.u=311sin(200πt+180°)V
C.u=220sin(628t+180°)V
D.u=-311sin100πtV
A.u=380sin314tv
B.u=537sin(314t+50°)v
C.u=380(314t+90°)v
D.380sin(314t-90°)v
A.i=20sin(100π-π/6)A
B.i=0.4sin(100πt-2π/3)A
C.i=0.4sin(100π+π/3)A
A.310W
B.320W
C.315W
D.300W
频系数mf和有效带宽BW;3.若调制信号uΩ(t)=3cos2π×103t(V),则m`f=?BW`=?