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Homework Statement
A 1 mile long copper wire has a resistance of 68 ohms. What will be its new resistance when doubling it over and using it as "one" wire
Homework Equations
?R=V/current
OK. More generally, how does resistance depend on length and cross-sectional area?I know that when it is cut in half R=34 ohms
No. Read this: http://hyperphysics.phy-astr.gsu.edu/hbase/electric/resis.html#c2"inverse square rule?
That's right. As that site explains, the resistance is inversely proportional to the cross-sectional area (which gives one factor 1/2) and directly proportional to the length (which gives a second factor of 1/2).the correct answer is 17 ohms...double width, 1/2 length =1/4 resistance?