Question

A 1200 ohms resistance of AC 0.07H inductance coil and a 0.001mF capacitor are in series across a 120V source determine.

a.frequency.
b.current.
c.impedance.

Answer 1

Is the inductive reactance of the coil 1200 ohms? If so:

a. Xl = 2pi*F*L = 1200 Ohms.
F=Xl/(2pi*L)=1200/(6.28*0.07)=2728.4 Hz.

b. Xc = 1/(2pi*F*C)
Xc=1/(6.28*2728.4*0.001*10^-6)=58333 Ohms
Z = Xl+ Xc=1200 + (-58333)=-57133 Ohms,
Capacitive. = 57133@(-90) Deg.
I = V/Z = 120/57133=2.1*10^-3A @ 90 Deg.

c. Z was calculated in under b.