Question

a wire of uniform area of cross section is stretched to four times its original length. by what factor does its resistivity change

Answer 1

'Resistivity' of the wire will remain the 'same'.

Explanation:

Resistivity is a 'property of a material' that does not depend upon physical factors such as length, cross section area or thickness. It depends on the nature of the material.

However the resistance of the material will definitely change with change in length, volume or cross section area.  

Formula for Resistance:

R = ρl/A

Where,

R = resistance  

A= Area of cross section

ρ= resistivity of the material

Answer 2

Answer:

Resistivity is a 'property of a material' that does not depend upon physical factors such as length, cross section area or thickness. It depends on the nature of the material.