The resistance of a wire is RΩ. If it is melted and stretched to n times its original length, its new resistance will be
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Solution
Resistance of wire is R=ρlA ⇒R=ρl.lA.l=ρl2V
After stretching, volume of wire will be constant ⇒R∝l2
So, if length increases n times
New resistance is R1=n2R