Question 414085
The electrical resistance of a wire varies directly as its length and inversely as the square of its diameter. If a wire with length 100cm and diameter 2 mm has a resistance of 1.5 Ohms, find the resistance of a wire with length 300cm and diameter 3mm. 

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r = k*L/d^2
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Solve for "k" using "If a wire with length 100cm 
and diameter 2 mm has a resistance of 1.5 Ohms".
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1.5 = k*100/2^2
100k = 6
k = 0.06
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Equation for this problem: 
r = 0.06*L/d^2
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Now "find the resistance of a wire with length 300cm and diameter 3mm". 
r = 0.06*300/3^2
r = 0.06*100/3
r = 2 Ohms
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Cheers,
Stan H.
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