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Resistivity

A wire of res...

Question

A wire of resistance R is stretched to twice of its original lenght. Find its new resistance

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Solution

Given resistance of wire = R Ω
R= ρL1/A1
When the wire is stretched to double its length, the radius will decrease as such the volume remains constant.
A1L1 = A2L2
A1L1 = A2×2L1
A2 = A1/2
Now, R'= ρL2/A2 = ρ×2L1/A1/2 = 4(ρL1/A1)
=4R1
So new resistance is 4 times of old one

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