Was there a mistake in our final exam question about resistance?

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Homework Help Overview

The discussion revolves around a final exam question regarding the calculation of resistance from a graph depicting current as a function of voltage. Participants are examining whether the method of calculating resistance using the formula R=ΔV/ΔI is appropriate when the graph does not pass through the origin, particularly in the context of non-ohmic behavior.

Discussion Character

  • Conceptual clarification, Assumption checking, Mixed

Approaches and Questions Raised

  • Participants discuss the validity of using R=ΔV/ΔI for calculating resistance in scenarios where the relationship between voltage and current is not linear. Some question the implications of the graph's shape on resistance calculations, while others reference definitions and examples from textbooks.

Discussion Status

The conversation is ongoing, with multiple interpretations of resistance being explored. Some participants express confusion regarding the exam question's wording and its implications for the definition of resistance, while others provide insights into the differences between chordal and differential resistance.

Contextual Notes

There is mention of a specific range of voltages (3V to 5V) and the behavior of resistance within that range, as well as references to textbook definitions that may not align with the exam question. Participants are also considering the implications of using different definitions of resistance in their calculations.

  • #31
Eitan Levy said:
In the answers only one answer was given.
In which case I'd want to see the exact wording of the question. At the very least it's unclear in the OP.

You could try writing to the examining board but most won't enter into correspondence. I'd be tempted to find a forum for professional electrical/electronic engineers in your country and post the question there. Dont post the answer initially, just see what replies you get. Perhaps see if you can't interest them in writing to the board to complain about the quality of the question.

Here in the UK the correct answer for this in a GCSE Plysics exam (taken at age 16) would be the range of values given by R=V/I.
 
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