Total Price:

There are no items in this cart.
Continue Shopping

microscopic form of ohms law

3 years ago


Answers : (1)


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

3 years ago

Post Your Answer

More Questions On Electric Current

Ask Experts

Have any Question? Ask Experts

Post Question

Answer ‘n’ Earn
Attractive Gift
To Win!!!
Click Here for details
solution to 2001 paaper 1 physics
Hii If you have any exact problem from the paper then ask that. It is absolutely next to impossible to answer such kind of queries. Thanks. . . . .
Sourabh Singh 7 months ago
Pl help in answering the question as attached.
Let’s say the current in 5 ohm branch is I. This current gets divided into 2 ohm resistor and 4 ohm resistor. Let current in 2 ohm branch be I 1 ,so current in 4 ohm branch will be I-I...
Aziz Alam 7 months ago
In real life, what is the actual direction of electric current? Is conventional current a incorrect concept?
Electric current doesn’t have any particular direction, it is due to flow of charge from higher potential to lower potential.
Saurabh Kumar 3 days ago
A point mass moves tangentially on a frictionless inner surface of a spherical shell whose inner radius R=1.4m, its velocity reaches its maximum and minimum at height h1=0.1m and h2=0.3m...
The question is unclear as it does not specify the orientation of the spherical shell and the point with reference to which the height values have been given. Please provide added...
Ajaykrishnan Jayagopal 5 months ago
what is the kirchooff integral theorem and its applications
Kirchhoff's integral theorem uses Green's identities to derive the solution to the homogeneous wave equation at an arbitrary point P in terms of the values of the solution of the...
Yash Baheti 7 months ago
Heat and work are equivalent.This means
We say that heat and work are equivalent as these energies are inter convertible. But note that there is some energy loss when the heat supplied to a system. That is a part of heat is lost...
Vasantha Kumari one year ago
View all Questions »