Flag Electric Current> microscopic form of ohms law...
question mark

microscopic form of ohms law

Harpreet Singh , 13 Years ago
Grade
anser 1 Answers
Ashwin Sinha

Last Activity: 13 Years ago

Dear Harpreet Singh,

Ohm's Law is the linear proportionality between current and voltage that occurs for most conductors of electricity. A graph of voltage against current is a straight line. The gradient is the resistance.

The most well known form of Ohm's law is V=IR, where V is the voltage, I is the current and R is the resistance. However there is another form of Ohm's law which often used by physicists that operates on a microscopic level, relating the current density J to the conductivity σ and the electric field, E.

To see how consider, the volume of material with faces of area A a distance l apart. With an e.m.f. V across the faces of the material

  • the current is proportional to the voltage V
  • the current is proportional to the surface area A
  • and the current is inversely proportional to the distance l.

The current is therefore,

I = VAσ/l.

R = l/Aσ

The proportionality constant σ is the conductivity of the material.

V/l = |E|, and J = I/A in the direction of E so in general we have the constitutive relation.

J = σE

 

                      Good Luck!!!!!!

 

 Plz. approve my answer, if you loved it, by clicking 'Yes' given below!!!!!!Plz. Plz. Plz.!!!!!!! Don't forget!!!!!!!!Smile

Provide a better Answer & Earn Cool Goodies

Enter text here...
star
LIVE ONLINE CLASSES

Prepraring for the competition made easy just by live online class.

tv

Full Live Access

material

Study Material

removal

Live Doubts Solving

assignment

Daily Class Assignments


Ask a Doubt

Get your questions answered by the expert for free

Enter text here...