rearranging resistivity formula

Hi,

I am looking at how the resistance of a wire differs with length. I have come up with a formula that shows that resistance = 0.3 x length for a particular type of wire. I am describing what this constant represents and by rearranging the resistivity formula I have got: R = p/A x L

when R represents resistance
p represent resistivity
A represents cross-sectional area
L represent length.

Is it right to arrange it like this? I have found other arrangements where R = p x L/A and does this show the same as what I have done, just in a different form? I found that by dividing the resistivity by the cross-sectional area I got the 0.3 in my formula yet have I gone about this the right way?

Any explanation or help will be great

Reply 1

zedtheimpaler

minnie

Hi,

I am looking at how the resistance of a wire differs with length. I have come up with a formula that shows that resistance = 0.3 x length for a particular type of wire. I am describing what this constant represents and by rearranging the resistivity formula I have got: R = p/A x L

when R represents resistance
p represent resistivity
A represents cross-sectional area
L represent length.

Is it right to arrange it like this? I have found other arrangements where R = p x L/A and does this show the same as what I have done, just in a different form? I found that by dividing the resistivity by the cross-sectional area I got the 0.3 in my formula yet have I gone about this the right way?

Any explanation or help will be great

The rearrangement is fine: R = (pL)/A

When you write it you can, if you want, take either the "p" or the "L" out of the brackets so you can write R = either p/A x L or L/A x p

So I suppose you constant of 0.3 must be p/A

The problem, assuming you made all your measurements at the same temperature, is that "p" is a constant but p/A isn't (unless you used wire of the same thickness every time, in which case it would be fine and should be mentioned in your write up)

If you used wire of a different thickness, you would get a different "constant"

I hope this is helpful

Reply 2

minnie

OP

1

It is very helpful! Thanks very much :smile:

rearranging resistivity formula

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