Calculating Impedance and Voltage Drop in an RLC Circuit

Click For Summary
The discussion focuses on calculating various parameters of a series RLC circuit with a resistor, inductor, and capacitor connected to an AC source. Key calculations include total impedance, total current, and voltage drops across each component, with specific values provided for resistance, inductance, and capacitance. The user encounters difficulty in determining the voltage drops, particularly in verifying the application of Kirchhoff's law. Another participant suggests that the issue may stem from a calculation error, leading to a resolution of the problem. The conversation emphasizes the importance of accurate calculations in analyzing RLC circuits.
ProPatto16
Messages
323
Reaction score
0

Homework Statement


A resistor, R = 100 Ω, an inductor, L = 0.20 H and a capacitor, C = 3 µF are connected in series across an ac source of VS = 100 V and frequency, f = 200 Hz. Calculate the following for this series circuit:
a) the total circuit impedance (Zt)
b) the total circuit current (IS)
c) the voltage drop across each component (VR, VL and VC)
d) the phase angle between VS and It.
e) Draw the phasor diagram of voltages and current for the circuit.
f) What is the frequency of the ac source for maximum current to flow?
g) What is the quality factor, Q, of the circuit at the frequency calculated in part f)?




The Attempt at a Solution



R = 100 ohms
L = 0.2 henries
C = 3*10^-6 farads
Vrms = 100V therefore Vmax = 100*sqrt2 = 141.42
freq = 200Hz therefore w = 1256.64
XL=wL=251.327
Xc=1/wc=265.26

Z = sqrt[(R^2 + (XL-Xc)^2] = 100.97
Irms = Vrms/Z = 0.99 therefore Imax = 0.99*sqrt2 = 1.4

now here is where I am stuck... the voltage drop...
Voltage drop across resistor, VR = R*Imax = 140V
Voltage drop across inductor, VL = XL*Imax = 352.03
Voltage drop across capacitor, VC = Xc*Imax = 371.51

and kirchhoff says Vmax^2 = VR^2 + (VL-VC)^2

subbing in... Vmax = 74.16 which is wrong... since Vmax = 141.42



Any ideas?
 
Physics news on Phys.org
I think you just plugged it into your calculator wrong. I got the right answer following what you did.
 
oh god -.- thank you.
 
The book claims the answer is that all the magnitudes are the same because "the gravitational force on the penguin is the same". I'm having trouble understanding this. I thought the buoyant force was equal to the weight of the fluid displaced. Weight depends on mass which depends on density. Therefore, due to the differing densities the buoyant force will be different in each case? Is this incorrect?

Similar threads

  • · Replies 8 ·
Replies
8
Views
2K
  • · Replies 6 ·
Replies
6
Views
2K
Replies
2
Views
2K
Replies
2
Views
2K
  • · Replies 9 ·
Replies
9
Views
2K
  • · Replies 5 ·
Replies
5
Views
2K
  • · Replies 2 ·
Replies
2
Views
2K
Replies
1
Views
2K
Replies
8
Views
2K
Replies
4
Views
6K