Question

A uniform wire of resistance 50 ohms and having resistivity of 1.59*10^-8 ohm is melted and recast into wire of length double that of original. what would be the resistance and resistivity of new wire formed

Answer 1

Here resistivity does not change because it's depends on metarial of wire which is same
But r is directly promotional to L^2
HENCE R'=50*2*2=200 ohm