How Does Current Vary with Voltage in Parallel Filament Lamps?

In summary, the conversation discusses an experiment to investigate the relationship between current and potential difference for two identical filament lamps wired in parallel. The results suggest that the relationship can be described by the equation i=kv^n, with n representing the gradient and k representing the y-intercept. Two graphs were plotted to obtain the values for n and k, with n=1 and k=50 for one filament lamp, and n=0.68 and k=16.5 for two filament lamps in parallel. The conversation also mentions a formula for m number of lamps, but it is unclear how the number of lamps affects the equation. The conversation suggests using MATLAB and polyfit to obtain more accurate values for n and k, and to plot the original
  • #1
A-BEE
3
0

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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  • #2
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?
 
  • #3
it was a lab so the most i can show you are my lab instructions and my graphs
 
  • #4
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
 
  • #5
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.
 
  • #6
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...
 

FAQ: How Does Current Vary with Voltage in Parallel Filament Lamps?

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