SOLUTION: the electrical resistance of a wire directly with its length and inversely with the square of its radius. if a wire with radius 1.3 millimeter and length 14 meters has a resistance

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Question 308313: the electrical resistance of a wire directly with its length and inversely with the square of its radius. if a wire with radius 1.3 millimeter and length 14 meters has a resistance of 17 ohms, what will be the resistance of a wire with radius 0.8 millimeter and length 20 meters.
Answer by ankor@dixie-net.com(22740) About Me  (Show Source):
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the electrical resistance of a wire directly with its length and inversely with the square of its radius.
if a wire with radius 1.3 millimeter and length 14 meters has a resistance of 17 ohms, what will be the resistance of a wire with radius 0.8 millimeter and length 20 meters.
:
let k = the constant of the variation
:
R = %28L%2AK%29%2Fr%5E2
:
When R = 17 ohms
%2814%2AK%29%2F1.3%5E2 = 17
%2814%2AK%29%2F1.69 = 17
14K = 17 * 1.69
14k = 28.73
k = 28.73%2F14
k = 2.052
:
Find R when L = 20, r = .8
R = %2820%2A2.052%29%2F.8%5E2
R = 41.043%2F.64
R = 64.13 ohms