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Question
A metal wire of resistance 6 Ω is stretched so that its length is increased to twice its original length. Calculate its new resistance.
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Solution
R1 = 6Ω, R2 = ?
l1 = l, l2 = 2l
a1 = a, a2 = `a/2`
p1 = p2
`(R_1a_1)/(l_1) = (R_2a_2)/(l_2)`
`6xxa/l = (R_2xxa/2)/(2l)`
`6 = (R_2xx1/2)/2`
`6 = R_2 xx1/2xx1/2`
6 × 2 × 2 = R2
R2 = 24Ω
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