SOLUTION: At a fixed temperature, the risistance R of a wire varies directly as the length l and inversely as the square of its diameterd. If the risistance is 0.8 ohm when the diameter is 1

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Question 374822: At a fixed temperature, the risistance R of a wire varies directly as the length l and inversely as the square of its diameterd. If the risistance is 0.8 ohm when the diameter is 1mm and the length is 200 cm,what is the risistance when the diameter is 2 mm and the length is 1250 cm.
Answer by amoresroy(361) About Me  (Show Source):
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At a fixed temperature, the risistance R of a wire varies directly as the length l and inversely as the square of its diameterd. If the risistance is 0.8 ohm when the diameter is 1mm and the length is 200 cm,what is the risistance when the diameter is 2 mm and the length is 1250 cm.
R = c*l/d^2
0.8= c*200/1^2
c = .004
Solve for R if
d=2mm and l=1250cm
R= .004*1250/2^2
R= 1.25
The resistance is 1.25 ohm when the diameter is 2 mm and the length is 1250 cm.