To solve ISRO paper, Can I post my doubt questions here in this thread

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Discussion Overview

The discussion revolves around participants seeking assistance with a multiple choice question paper from ISRO 2012, specifically focusing on various questions related to electrical circuits and the behavior of diodes in AC circuits. The scope includes homework-related inquiries and technical explanations regarding circuit analysis and harmonic distortion.

Discussion Character

  • Homework-related
  • Technical explanation
  • Debate/contested

Main Points Raised

  • Devanand T asks if it is acceptable to post questions from the ISRO paper for help.
  • Another participant suggests that posting one question at a time along with relevant equations and attempts at solutions is appropriate.
  • Devanand T presents question 18, which concerns the harmonics of a current wave in an AC circuit with diodes, and proposes option (a) as the answer.
  • A participant questions the assumption of ideal diodes, arguing that the voltage drop across real diodes would affect the output waveform, leading to distortion and the presence of harmonics.
  • Another participant proposes a nonlinear model for the diode's behavior, suggesting that all harmonics could be present in the output.
  • One participant challenges this model, recommending that a sketch of the expected current waveform be attempted to clarify the situation.

Areas of Agreement / Disagreement

Participants express differing views on the behavior of diodes in the circuit and the implications for harmonic generation. There is no consensus on the correct approach or the assumptions regarding diode behavior.

Contextual Notes

Participants have not fully resolved the assumptions regarding ideal versus real diodes, and the implications of these assumptions on the output waveform and harmonic content remain unclear.

dexterdev
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I have a multiple choice question paper from ISRO 2012.

http://www.isro.org/pdf/EC-2012.pdf

Can I post doubtful questions in this thread. Is there someone to help me.

-Devanand T
 
Last edited by a moderator:
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dexterdev said:
I have a multiple choice question paper from ISRO 2012.

http://www.isro.org/pdf/EC-2012.pdf

Can I post doubtful questions in this thread. Is there someone to help me.

-Devanand T

I think as long as you post about just one question at a time, and list the Relevant Equations and show your sincere Attempt at a Solution, it should be okay to do for now.
 
Last edited by a moderator:
Thank you sir, I will do that..
 
Which question do you want to tackle first?
 
The circuit diagram is shown in the attached file..q18

The question 18 is regarding harmonics of current wave in the ac circuit having diodes.

My answer if option (a) , any mistake here..
 

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Last edited:
dexterdev said:
The question 18 is regarding harmonics of current wave in the ac circuit having diodes.

My answer if option (a) , any mistake here..
I don't think we can assume ideal or idealized diodes here, for the simple reason that if the source is an ideal sinusoid, and the diodes were to drop a fixed 0.6V, then where does the remainder of the voltage disappear?

So I picture operation over the diode's exponential curve (which extends to infinity), and giving rise to a distorted alternating current (perhaps missing a portion around the zero crossings).

Being a distorted sinewave, it contains harmonics.
 
Ok thankyou sir , will come with other doubts in the same paper..
 
dexterdev said:
Ok thankyou sir , will come with other doubts in the same paper..
I haven't answered the question, apart from ruling out (a).
 
sorry
 
  • #10
As diode is having a nonlinear behaviour can we say the output is like
I = a + b v^1 + c v^2 + d v^3 + ....

so will all harmonics come...
 
  • #11
dexterdev said:
As diode is having a nonlinear behaviour can we say the output is like
I = a + b v^1 + c v^2 + d v^3 + ....

so will all harmonics come...
I don't think so. I think you should try to sketch the expected current waveform.
 
  • #12
ok I will try.
 
  • #13
7th question

Hi pf,
Please see the attached figured , it is the 7th question.
 

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    31.5 KB · Views: 495

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