microscopic form of ohms law

3 years ago

Share

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
Vouchers
To Win!!!
Click Here for details
Is it possible to charge a smart phone with an apple or banana?
 
 
watch this on you tube, but I also think that it is fake.
 
Indu 5 months ago
 
nops.. i don`t think soo....
 
Vimlendra Singh 6 months ago
simple but well defined strcture and working of the electric motor,it confuses me a lot
 
 
Have a look here howstuffworks.com/motor1.htm
 
Ashwin 2 months ago
Two coils of resistance 3 Ohm and 6 Ohm . are connected in series across a battery of emf 12v . find electrical energy consumed in 1 min in each resistance when these are connected in...
 
 
Dear Student There is something missing in the answer by book because you were to calculate energy in each resistance which is not same in the two resistors. The complete answer should be...
 
shashi K Sharma one month ago
View all Questions »