Ask A Scientist© Physics Archive

> > >  name       Siobhan
> > >  status     student
> > >  age        15
>
> > >  Question - does the resistance double as you double the length of a
> > > piece of wire?
>
>
>Is this a trick question? Seems like it might be... Yes, the resistance is
>proportional to the length. Therefore if the length is doubled, the
>resistance is doubled. Interestingly, the relationship of resistance to
>diameter is not so simple and the frequency of the current affects the
>resistance (actually, the impedance... have you met this term?).
>
>Larry Krengel
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>Yes.
>
>Tim Mooney

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>Yes, the resistance of a wire is directly proportional to the length and
>inversely proportional to the Area. Hence doubling the length of a wire
>increases the resistance by a factor of two, doubling the area would
>decrease the resistance by half. The proportionality constant relating
>resistance to the length and area of a wire is the resistivity of the wire.
>Resistance=Resistivity x length/area
Dr. Myron
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>The resistance of a wire, under nearly constant temperature conditions, is
>directly proportional to length and inversely proportional to the cross
>sectional area.
>
>R = (rho)L/A
>
>R is the resistance
>rho is the characteristic of the material, and is a measured
>quantity. Copper has a different
>         rho than say, carbon.
>L is the length of the wire
>A is the effective cross sectional area of the wire.
>
>Most introductory college physics texts have more information about this.
>
>---Nathan A. Unterman
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