document.write( "Question 209297: The resistance of a wire varies directly with its length and inversely with the square of its diameter. If 100 feet of wire with diameter 0.01 inch has a resistance of 80 ohms, what is the resistance of 90 feet of the same type of wire if its diameter is 0.04 inch?\r
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Algebra.Com's Answer #158223 by stanbon(75887)\"\" \"About 
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The resistance of a wire varies directly with its length and inversely with the square of its diameter. If 100 feet of wire with diameter 0.01 inch has a resistance of 80 ohms, what is the resistance of 90 feet of the same type of wire if its diameter is 0.04 inch?
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\n" ); document.write( "r = k*L/D^2
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\n" ); document.write( "Find \"k\":
\n" ); document.write( "80 = k*100/0.01^2
\n" ); document.write( "80 = k*100/0.0001
\n" ); document.write( "80 = k/1,000,000
\n" ); document.write( "k = 80,000,000
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\n" ); document.write( "Now you know the equation is
\n" ); document.write( "r = (80,000,000)L/D^2
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\n" ); document.write( "what is the resistance of 90 feet of the same type of wire if its diameter is 0.04 inch?
\n" ); document.write( "r = (80,000,000)90/(0.04)^2
\n" ); document.write( "r = 4.5x10^12 ohms
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\n" ); document.write( "Cheers,
\n" ); document.write( "Stan H. \n" ); document.write( "
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