How Does Current Vary with Voltage in Parallel Filament Lamps?

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Discussion Overview

The discussion revolves around the relationship between current and voltage in parallel filament lamps, specifically investigating how current varies with potential difference when multiple identical lamps are connected in parallel. The context includes experimental results, mathematical modeling, and analysis of data obtained from a lab experiment.

Discussion Character

  • Homework-related
  • Technical explanation
  • Debate/contested

Main Points Raised

  • One participant suggests a model where current (i) is proportional to voltage (v) raised to a power (n), expressed as i = kv^n, and provides experimental results for one and two filament lamps.
  • Another participant questions the validity of the proposed formula, expressing skepticism about its applicability to different numbers of lamps and suggesting that parameters should change with the number of lamps.
  • A participant mentions the difficulty in providing source data, indicating that only lab instructions and graphs are available.
  • One participant advises using MATLAB and polyfit to derive values for n and k from the data, suggesting that conclusions should be drawn from the plotted function.
  • Another participant expresses surprise at the form of the equation provided, stating that while it is not incorrect, they would not expect it to yield different values of n for different numbers of lamps.

Areas of Agreement / Disagreement

Participants express differing views on the appropriateness of the proposed model and the implications of the experimental results. There is no consensus on the validity of the formula or the expected behavior of current with varying numbers of lamps.

Contextual Notes

Participants note limitations in the discussion, such as the lack of source data and the potential for different interpretations of the results based on the number of lamps connected in parallel.

A-BEE
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Homework Statement


to investigate the variation of current and potential difference for two identical filament lamps and use the results of the experiment to suggest how current varies with potential difference for any number of identical lamps wired in parallel.

it is suggest that i=kv^n
therefore log i = log k + nlogv

two graphs of log i against log v ( one for a filament lamp and then the other for two filement lamps in parallel) were plotted to obtain n which is the gradient and k the y intercept
results for one filament lamp
n= 1 k=50
results for two filament lamp in parallel
n = 0.68 k =16.5

Homework Equations


comment on the values obtained for n and k
values for n and k expected for three lamps in parallel
and an equation for m number of lamps which describes the relationship between i and v

The Attempt at a Solution


for my comment on the values i can tell that the values become less therefore id expect that if a third lamp was added it would further decrease but that's all i get from this [/B]
 
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A-BEE said:
it is suggest that i=kv^n
Why? And how does the number of lamps come into this formula?
It does not make sense to use that formula for different numbers of lamps. Obviously something will change, while the parameters of your formula should not.

Can you show your source data?
 
it was a lab so the most i can show you are my lab instructions and my graphs
 
im having trouble uploading the instructions but everything I've posted is what's on the paper the value given are values i had obtained from plotting my results from the lab
 
My advice if that really is the question:

Use MATLAB and polyfit to obtain ##n## and ##k##.

Use those to plot the original function ##i = kv^n##.

Make your conclusions from there, although that is assuming that really is the equation you were given.
 
I would be surprised if that equation was given. It is not wrong, but I would not expect that form. Anyway, two lamps should not give a different n.

If you don't show your source data (if uploading does not work, you can copy some values by hand) it is hard to see what went wrong...
 

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