Question:
I'm doing my GCSE (higher level) and was asked to
investigate resistance of a wire. the lengths are to be changed but the
content of the wire is to stay the same. Are there any formula linked
with resistance and length and also are there any experimental methods
to be used? Finally any other information linked with this.

Replies:
Hello,

I think I have responded to another question regarding wire resistance
earlier on this site. In any case:

Resistance = Resistivity of wire material x (Length/cross sectional area).

If volume V=LA of the material is constant, the equation above can be
written as:

Resistance = Resistivity x (Length/(V/L)) = Resistivity x (L^2/V).

Therefore, resistance is proportional to length squared.
To measure the resistance, R, one can apply a known voltage across the
resistor, measure the current flow, I, and use Ohm's Law to get R from V=RI.

AK

Dr. Ali Khounsary
Advanced Photon Source
Argonne National Laboratory
Argonne, IL 60439

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