Is This Impedance Calculation Correct?

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In summary, impedance is a measure of the total opposition to an alternating current in a circuit and is calculated using the formula Z = R + jX. It takes into account the combined effects of resistance, capacitance, and inductance and is measured in ohms. Resistance, on the other hand, only accounts for the opposition caused by the material of the circuit. It is important to verify impedance in order to ensure proper functioning of the circuit and to identify any potential problems. Impedance can be affected by factors such as temperature, frequency, and the type of material and wiring used in the circuit.
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AntiStrange
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Homework Statement


Calculate the circuit's impedance Z between input and ground for an applied sinusoidal voltage with frequency f = 1000Hz, and express Z in the form [itex]re^{i\theta}[/itex]

There is a picture that goes with it, it's just a function generator (makes a sinusoidal AC voltage) connected in series with a 0.1μF capacitor, and a 1kΩ resistor.

I think I solved it, but I would just like it if someone could verify that I did it correctly as it is going into a lab report.


Homework Equations


i.[tex]Z = \sqrt{R^{2} + (X_{L} - X_{C})^{2}}[/tex]
where X_L is for a transistor (none exists in the circuit so it's zero) and X_C is for the capacitor

ii. [tex]X_{C} = \frac{1}{\omega C}[/tex]

iii.[tex]tan(\phi) = \frac{\omega L - 1/\omega C}{R}[/tex]

All equations extracted from "University Physics by Young & Freedman 11th edition



The Attempt at a Solution


From Eq i, I just plugged in 1kΩ for the resistor, and X_L is zero, and I found X_C from Eq ii (where C is the 0.1μF capacitor and ω is 2π*1000Hz).
This gave me a value for Z of 1879.6Ω.

Then, to find it in the form [itex]re^{i\theta}[/itex], more specifically it should be:
[tex]re^{i(\omega t + \phi)}[/tex]
I know everything but φ, so I used Eq iii.
Again, L was zero so the first term in the numerator canceled out, and I found φ to be:
- 1.010 (radians).

So my final answer is:

[tex]1879.6 e^{i(2000\pi t - 1.01)} \Omega[/tex]

Is that all correct?
thanks.
 
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  • #2


Your calculations seem to be correct. The impedance Z is indeed 1879.6Ω and can be expressed in the form re^{i\theta} as you have shown. Great job!
 
  • #3


Your solution looks correct. Just make sure to double check your calculations and units. Also, it might be helpful to include a brief explanation of your steps and equations used in your lab report. Overall, great job on solving the problem!
 

FAQ: Is This Impedance Calculation Correct?

What is impedance?

Impedance is a measure of the total opposition to an alternating current (AC) in a circuit. It is a combination of resistance, capacitance, and inductance and is measured in ohms (Ω).

How do you calculate impedance?

Impedance is calculated using the formula Z = R + jX, where R is the resistance in ohms and X is the combined reactance in ohms. Reactance can be either capacitive (Xc) or inductive (Xl), and is calculated using X = 1/ωC (for capacitors) or X = ωL (for inductors), where ω is the angular frequency in radians per second and C and L are the capacitance and inductance, respectively.

What is the difference between impedance and resistance?

Resistance is a measure of the opposition to current flow in a circuit, while impedance is a measure of the total opposition to an alternating current in a circuit. Resistance only accounts for the opposition caused by the material of the circuit, while impedance also takes into account the effects of capacitance and inductance.

Why is it important to verify impedance?

Verifying impedance is important because it ensures that the circuit is functioning correctly and that the correct components are being used. It also helps to identify any potential problems or malfunctions in the circuit.

What factors can affect impedance?

Impedance can be affected by various factors such as temperature, frequency, and the type of material used in the circuit. Additionally, the length and thickness of the wires used can also affect impedance.

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