How Is Resistance Calculated in Different Bias Regions of a Diode?

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Discussion Overview

The discussion revolves around the calculation of resistance in different bias regions of a diode, specifically in the context of a homework problem from a past exam paper. Participants are exploring the application of relevant equations and attempting to solve for resistance values based on provided voltage and current measurements.

Discussion Character

  • Homework-related
  • Mathematical reasoning

Main Points Raised

  • The original poster presents a homework problem and outlines their attempt at calculating resistance values using specific equations.
  • Some participants request clarification by asking for the question to be posted directly instead of linking to an external site.
  • The original poster acknowledges the request and attempts to provide the question after fixing the link issue.

Areas of Agreement / Disagreement

There is no consensus on the calculations presented, as the focus is primarily on clarifying the question rather than resolving the mathematical aspects of the problem.

Contextual Notes

Participants have noted issues with accessing the external link to the homework question, which may limit the discussion's depth regarding the specific calculations and concepts involved.

eximius
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Note: This is a past paper, I'm simply revising for an exam. But I thought that this was the best forum to stick it in.

Homework Statement



http://exampapers.cf.ac.uk/papers/engin/en1051/en1051a09.pdf

Section A, Q1 c

[PLAIN]http://img684.imageshack.us/img684/9695/questionm.jpg

Homework Equations



R1 = V1/I1
Rp = (V2-V1)/(I2-I1) = R1||R2
R2 = RpR1/(Rp-R1)

The Attempt at a Solution



R1 = 0.5/280x10-6 = 1785.71 ohms
Rp = (0.54 - 0.5) / (680x10-6 - 250x10-6) = 0.04 / 4x10-4 = 100ohms = R1||R2
R2 = RpR1/(Rp-R1) = 178571 / (-1685.71) = -105.9322185 = -105.93 ohms
V1 = 0.5V

Diagram -

[PLAIN]http://img407.imageshack.us/img407/4486/diagrame.jpg

Forgive the wrong symbols, difficult with paint.
 
Last edited by a moderator:
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That link:

A username and password are being requested by https://exampapers.cf.ac.uk . The site says: "Enter your Cardiff University username & password"

Can you post the question rather than link to it please.
 
Last edited by a moderator:
Zryn said:
That link:



Can you post the question rather than link to it please.

Sorry I've fixed it.
 
Bump, sorry.