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RLC Circuits and Resonance - Engineering

Q1:

A resistor of 3 k, a 0.05 F capacitor, and a 120 mH coil are in series across a 5 kHz, 20 V ac source. What is the impedance, expressed in polar form?

A 636 

B 3,769 

C 433 

D 4,337 

ANS:D - 4,337 

Given parameters; L = 120 mH, R = 3*10^3 ohm,

c = 0.05 uF and F = 50 kHz.

XL = 2*3.14*5*10^4*1.2*10^-1 = 3728 ohm.

Xc = 1/2 (3.14*5*10^4*5*10^-8) = 636.94 ohm.

Magnitude |Z| = (R^2+(XL-XC)^2)^1/2 = 4337.3 ohm.

Tan (Q) = (XL-XC)/R = (3728-636.94)/3000 = 3091.06/3000 = 1.03035333.

Q = tan^-1 (1.03035333) = 45.85 degree.

Therefore the impedance as polar form is Z=|Z|at angle of Q = 4337.3 ohms at angle of 45.85 degree.

So as me the answer is not given here; no answer!