Question

Obtain ohm's law from the expression for electrical conductivity

Answer 1

Explanation:

The expression for electrical conductivity is J = σ. E ; where J is electric current density, σ is electrical conductivity and E is electric field.

Again if R = resistance of conductor

ρ= resistivity of conductor

L = length of conductor

A = area of cross section of conductor

V = voltage applied between two ends of the conduct

I = electrical current through conductor

Then J = I / A

R = ρL / A or, σ = 1/ρ = L / RA

E = V/L

So I/A = (L / RA) × ( V/L)

Arranging we get V = I × R which is well known ohm's law.