Question

write a note on finding the expression for the resistivity of material? ​

Answer 1

The resistivity of a material is defined in terms of the magnitude of the electric field across it that gives a certain current density. ... For example, keeping the material resistivity constant, the resistance of the sample can be increased by increasing the length, or decreasing the cross sectional area.

Answer 2

resistivity of the material is equals to resistance multiply by area of a cross section divided by length of material

it means that if the resistivity of a material is rho

and area of a cross section of a material is A

length of the material is l

resistance of the material is R

will be expressed as p = R * A/l

by reading a question carefully you can find the value of resistance area of a cross section and length of material
hence can find the value of resistivity