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Name: Siobhan
Status: student
Age: 15
Location: N/A
Country: N/A
Date: 2000-2001

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


Tim Mooney

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

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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