Transient Response of Electrical Network

Click For Summary

Discussion Overview

The discussion revolves around the transient response of electrical networks, specifically focusing on the behavior of current and voltage in capacitive and inductive circuits, as well as the implications of resistance on oscillations. Participants are addressing homework problems related to these concepts.

Discussion Character

  • Homework-related
  • Debate/contested
  • Mathematical reasoning

Main Points Raised

  • One participant states that since current leads voltage in a given question, the impedance is capacitive and questions the book's answer.
  • Another participant argues that transient (damped) oscillations are still considered oscillations, challenging the assumption that resistance must be zero for oscillations to occur.
  • A participant inquires about the complex impedance in a specific exercise, seeking clarification on its calculation.
  • One participant presents a calculation for impedance and concludes that the phase angle must be zero for resistance, suggesting that the book's answer may be incorrect.
  • Another participant expresses agreement that there seems to be an error in the book's answer for the exercise in question.

Areas of Agreement / Disagreement

Participants do not reach a consensus, as there are competing views regarding the role of resistance in oscillations and the correctness of the book's answers. Disagreements are evident in the interpretation of transient oscillations and the implications for impedance.

Contextual Notes

Participants note that assumptions regarding resistance and its impact on oscillations are not fully resolved, and there is uncertainty about the correct interpretation of the book's answers.

jaus tail
Messages
613
Reaction score
48

Homework Statement


upload_2018-1-24_12-11-37.png


Homework Equations


In Capacitance current leads voltage
In Inductance current lags voltage
For oscillations R = 0

3. The Attempt at a Solution

Since current is leading voltage in above question, impedance is capacitive.
Book answer is D for both.
How?

And for 3rd question, should R be 0, else circuit is damped. Oscillations mean undamped system so R = 0.
 

Attachments

  • upload_2018-1-24_12-9-31.png
    upload_2018-1-24_12-9-31.png
    5.2 KB · Views: 517
  • upload_2018-1-24_12-11-37.png
    upload_2018-1-24_12-11-37.png
    8 KB · Views: 929
Physics news on Phys.org
jaus tail said:
And for 3rd question, should R be 0, else circuit is damped
No. Transient (damped) oscillations are also oscillations.
 
  • Like
Likes   Reactions: jaus tail
Two for the price of one ? What is the complex impedance ##Z## in exercise 2 ?
 
  • Like
Likes   Reactions: jaus tail
z = v / i = 200 sin (2000t +50) / 4 cos (2000t + 11.32)
= 50 sin (2000t + 50) / sin (2000t + 11.32 + 90) = 50 sin (2000t + 50) / sin (2000t + 101.32)
For this to be resistance the phase angle must be zero which doesn't happen. So I think D cannot be right answer. Resistance cannot vary with time so the sine term must be a constant and not a time variant.
 
I agree there must be something wrong with the book answer for exercise 2.
 
  • Like
Likes   Reactions: jaus tail

Similar threads

  • · Replies 15 ·
Replies
15
Views
3K
  • · Replies 6 ·
Replies
6
Views
3K
  • · Replies 2 ·
Replies
2
Views
2K
Replies
7
Views
2K
  • · Replies 5 ·
Replies
5
Views
2K
  • · Replies 17 ·
Replies
17
Views
6K
Replies
2
Views
3K
  • · Replies 2 ·
Replies
2
Views
1K
  • · Replies 4 ·
Replies
4
Views
1K
  • · Replies 5 ·
Replies
5
Views
2K