# Resistivity Formula

## Resistivity Formula

Simply resistivity or Electrical resistivity is the resistance of the flow of current from one end to the other in a material. Electrical resistivity is a simply accessible and informative quantity to describe the material. It is the reciprocal of electrical conductivity. Resistivity is symbolized by ρ. It is directly proportional to the resistance of the material and the length of the material and inversely proportional to the area of cross section of the provided material. Formula for resistivity is,

$\rho\,&space;=\,&space;\frac{RA}{l}$

Where, ρ is the resistivity, R is the resistance, l is the length of the material and A is the area of cross-section.

Resistivity Solved Examples

Let us take a look on some of the numerical of resistivity in this segment.

Problem 1: Compute the resistivity of the given material whose resistance is 2Ω; area of cross section and length are 25cm2 and 15cm respectively?

It is known that,
R = 2Ω, l = 15cm = 0.15m and

A = 25cm2 = 0.25m2
Resistivity formula is articulated as,

$\rho\,&space;=\,&space;\frac{RA}{l}$

$\rho\,&space;=\,&space;\frac{2\times&space;0.25}{0.15}\,&space;=\,&space;3.333\Omega&space;m$

Problem 2: The length and area of a wire is given as 0.2m and 0.5m2 respectively. The resistance of that wire is 3Ω, Compute the resistivity?

It is known that,
R = 3Ω, l = 0.2m and A = 0.5m2
Resistivity formula is articulated as,

$\rho\,&space;=\,&space;\frac{RA}{l}$

$\rho\,&space;=\,&space;\frac{3\times&space;0.5}{0.2}\,&space;=\,&space;7.5\Omega&space;m$

#### Practise This Question

The Wien’s displacement law express relation between