Redrawing Circuits for Diode Analysis: Is It Valid?

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Homework Help Overview

The discussion revolves around the validity of redrawing a circuit for diode analysis, specifically focusing on the behavior of voltmeters and diodes within the circuit. The subject area includes circuit analysis and diode characteristics.

Discussion Character

  • Exploratory, Assumption checking, Conceptual clarification

Approaches and Questions Raised

  • Participants explore the implications of neglecting the conductance of voltmeters and the current through a non-conducting diode. Questions arise regarding the assumptions made about the ideal behavior of the components involved, particularly the reverse-biased diode.

Discussion Status

Some participants express confidence in the proposed approach to redraw the circuit, while others seek clarification on the terminology used by the original poster's teacher regarding the characteristics of the reverse-biased diode. The conversation indicates a productive exchange of ideas without reaching a definitive consensus.

Contextual Notes

There is mention of a teacher's guidance regarding the resistance of the reverse-biased diode, which may influence the understanding of the circuit analysis. The original poster acknowledges a potential typo in their description, indicating a need for precision in communication.

QueenFisher
in the diagram below, the voltmeters are as near to perfect as possible, the cell has negligible internal resistance. the red blob is a conducting diode, and the green blob is non-conducting. the coloured boxes are resistors. in order to work out the current through the red diode, is it ok to redraw the circuit as shown on the left? i figured that as the voltmeters have very high resistance, there'd be virtually no current through them, and none at all through the green diode. is this an ok way of looking at it?

http://home.ripway.com/2005-7/361234/circuit.bmp
 
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Negligible Conductances

I think you are on the right track. The conductance of Voltmeters can be neglected if they are in parallel with a much lower resistance element. Likewise, the current through the "non-conducting" diode can be neglected if it is much less than that through the reddish rectangle. If it is an ideal diode, then the current under reverse bias is zero, and your approximation is exact.
 
yes my teacher told me to take the resistance of the reverse-biased diode as zero, so i hope it will work.

thanks for checking it!
 
I think you are all set, but didn't your teacher mean that the current of the reverse biased ("non-conducting") diode is zero, or the conductance of the reverse biased diode is zero, or the resistance of the reverse biased diode is infinite?

Best Regards,
Walter
 
sorry 'bout that, i typed it wrong. :blushing: thanks for noticing.
 
Don't mention it -- I thought it was a typo, but wanted to make sure.
 

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