electric circuit, AC, 幫幫我!2

(a) For resonance case, the resonance frequency fo = 1/(2*pi*ROOT(2*4e-3)) = 1.779Hz or 11.18rad/s.

(b) If the voltage source is v=10cos(wt), for this case, w = 2pi*f = (2)(pi)(1.779) = 11.18rad/s.
XL = j(11.18)(4e-3) = j0.04472ohm
XC = -j0.04472ohm
Zeq = (1 / ( [1 / (10+j0.04472) ] + [ 1 / (-j0.04472) ] ) ) + 150 = 150<-0.01708 ohm
Converting the v = 10cos(wt) to the polar form, v = 10<0.
io = (10<0) / (150<-0.01708) = 0.0667<0.01708A
Changing the io to the rectangular form, io = 0.0667cos(11.18t + 0.01708) A