How a RESISTOR really works?

[sinatra]

resistor how stuff works

Can anyone explain or give webpage links on how a resistor really works?

I'm not talking about ohm's law. This we know.

I would like to know the physics behind....

S.

 

[IanP]

how a resistor works

As you can imagine, resistance will depend on a material a resistor is made of.
For any given substance, resistance depends upon length and diameter of the conducting pathway. Resistance varies directly with length and inversely with cross-sectional area of the pathway.
In other words, you can express a resistance as:
R=ρ*L/A, where ρ represents resistivity of a material, L=length, and A=cross-sectional area.
(The values of ρ for materials such as silver-the best known conductor-, copper, gold, .. etc, you can find in easily somewhere on the net).
Is it enough, or would you like to go into atom(s)-electron(s) structure of a resistive material?
regards ..
InaP

 

[AviH]

howstuffworks resistors

Hi,
I Guess that no one really know....
If i'm not mistaking the theory states that friction is responsible for the
resistance action.

 

[sinatra]

how a resistor work

I find unbelievable that we don't know how the simplest of the electronics components we have works.....

That's why i also opened this post.

Of course I know the Ohms law and the resistivity relation (thanks IanP, anyway):

What I wanted to know is how the resistor really works, the microscopic behaviour, the physics behind it.....

I remember that about many many years ago one of my professors in the University also complained that no one knew how to explain how the resistor really works and that it was a shame. He described then the problem of the mobility of the charges in a conductor with its basically random behaviour (brawnian motion...) and what happens when an electric field is applied.

Just using simple equations describing the movement of the electron relating to current density, displacement speed, electric field, acceleration, electric force, etc... in a conductor he could easily show how the resistor works and what the resistance means in terms of the physics that govern this component. Somehow it is not difficult to prove that the resistance is really a constant and why.....

But unfortunately I don't remember anymore this explanation and I don't have access to this anymore.....pitty.

I feel like I'm back to the beginning....

Anyone can help us???

S.

 

[hermin]

explain show how a resistor works

just think of electron flow as fluid flow...like water flowing inside a pipe....resistance of the water flow is dependent on the width of the pipe...the narrower the pipe the harder for the water to flow...

use this analogy to relate the current, voltage and resistance ... thats what my high school teacher told us...

in electrons, it also depends on the cross sectional area of the conductor, the resistivity of the material...and the length of the conductor..

 

[alvarorahul]

howstuffworksresistors

resistance is the opposition to the flow of current

when a voltage is applied to a resistor the electrons are pulled towards the positive terminal of the battery ( since it is negatively charged )

as it moves it collides with the atoms of the lattice and other scattering centres

thus it accelerates for sometime but then it is deaccelerated and this is the resistance of the material

due to this accel and deaccel the electron attains a constant average velocity known as drift velocity

 

[hermin]

resistor-how stuff works

try howstuffworks.com they provide a understandable exlanation of things around us...

 

[DoctorProf]

resistor

It is my understanding that resistance comes from scattering mecahnisms within the materail. As an electron moves under the influence of an electric field it will "run into things". These things could be atoms, potential wells, etc. When they hit these "things" the electron's velocity vector is altered causing scattering and a resistance to movement. This is the cause of internal resistance. The more scattering the more resistance.

Under high electric fields electrons in a materail will reach their velocity saturation limit (they can not move any faster) and the material becomes a non-linear resistor. Increases in electric field do not cause a cooresponding increase in current. This causes the materail to appear to become more resistive at very high fields.

Dr.Prof

 

[electron_boy]

how stuff works, resistors

hi
every material has its own property of resisting things flowing through itself. current flow is nothin but the electron flow. electron flow occurs when the conductance and valence band overlap with each other to a greater extent. resistance is large when they do not overlap or the overlap to a smaller extent. and also resistance depends upon the size of the material i.e cross section and the length.
any book on solid state physics may provide more info

 

[Lord Loh.]

resistors purpose thin wire

I belive that it is a resultant effect of free charge carriers, ionization energy and thermal disturbances.

If a high voltage is applied to the order that the ionization energy is reached then even rubber may conduct by breakdown....

Several of the above explainations are correct....

Don't we still understand how resistors work ?

Or are you looking for just the equations ?

 

[goalied00d]

understand how resistor works

If you have ever opened or broken a resistor open, you'll notice that there is a coil of wire, and this wire is very thin. This is the biggest reason why resistors, well, resist. You are trying to push a current or voltage through a very thin strand of wire and it will slow down because there isn't much room. The effect is something like punching a small hole in a 5 gallon jug of water.

The voltage or current is the water, and the thin wire would represent the small hole it has to travel through.

To counter a magnetic effect, when the first coil wrap is done, a second coil wrapped in the opposite direction is placed over the first wrap.