Question

Derive an expression to find resistivity

Answer 1

Answer:

"Resistivity formula"

The resistivity of a material is defined in terms of the magnitude of the electric field across it that gives a certain current density. It is possible to devise an electrical resistivity formula.

ρ=EJρ=EJ

Where:
    ρ is the resistivity of the material in ohm metres, Ω⋅m
    E is the magnitude of the electric field in volts per metre, V⋅m^-1
    J is the magnitude of the current density in amperes per square metre, A⋅m^-2

Many resistors and conductors have a uniform cross section with a uniform flow of electric current. It is therefore possible to create the more specific, but more widely used electrical resistivity formula or equation:

ρ=RAlρ=RAl

Where:
    R is the electrical resistance of a uniform specimen of the material measured in ohms
    l is the length of the piece of material measured in metres, m
    A is the cross-sectional area of the specimen measured in square metres, m^2

I Hope it will help!

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