Question

a wire of resistivity rho is melted and drawn into a new wire,twice of its original length what is the resistivity of new wire?

Answer 1

Hi there !!

Length = l
Area = A
Resistance = R =  ρ  l/A

R ∝ l
R is directly proportional to " l "


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New resistance = R'

Length = 2l
Area = A
R' = ρ  2l/A
    = 2 x ρ  l/A
   = 2 x R

The resistance of the new wire becomes two times the old resistance 

Answer 2

Resistivity is independent upon length of wire , resistance and area of cross section of wire . it is metallic property. it depends on material by which wire is formed . hence resistivity of new wire is same e.g rho