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1. I recently did an experiment on how the length of a nichrome wire affects the resistance. We got set some questions and I have no clue where to start
a) Use the relationship R= ρL/ A + Ro, A= πr^2 and r=d/2 to show that
R = (4ρ/ πd^2) L + Ro (where ρ= resistivity; Ro= resistance of connecting leads)
b) Hence show that ρ= Gπd^2/ 4 (where G= gradient), my gradient was 5 which seems too big but I think my multimeter was on a different sensitivity setting so I think it is ok. Also should the graph be a straight line from the origin because as the relationship is directly proportional that's what I thought but I don't know what it is about practicals, I always doubt myself- I hate them so much
Thanks in advance
2. (Original post by michelecorrrea)
I recently did an experiment on how the length of a nichrome wire affects the resistance. We got set some questions and I have no clue where to start
a) Use the relationship R= ρL/ A + Ro, A= πr^2 and r=d/2 to show that
R = (4ρ/ πd^2) L + Ro (where ρ= resistivity; Ro= resistance of connecting leads)
You can substitute in A= πr^2 into the equation R = (ρL/ A )+ Ro and play around with that a bit to get the desired result.

b) Hence show that ρ= Gπd^2/ 4 (where G= gradient), my gradient was 5 which seems too big but I think my multimeter was on a different sensitivity setting so I think it is ok. Also should the graph be a straight line from the origin because as the relationship is directly proportional that's what I thought but I don't know what it is about practicals, I always doubt myself- I hate them so much
Thanks in advance
I guess that you plotted the resistance (on the y-axis) against the length? If so, compare:

R = (4ρ/ πd^2) L + Ro to y = mx + c and see if you can get it from there.
3. (Original post by usycool1)
You can substitute in A= πr^2 into the equation R = (ρL/ A )+ Ro and play around with that a bit to get the desired result.

I guess that you plotted the resistance (on the y-axis) against the length? If so, compare:

R = (4ρ/ πd^2) L + Ro to y = mx + c and see if you can get it from there.
Yeah resistance is on the y axis
Thank you so much ... I love you more than words can express

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