# Thread: Resistance of a conductor

1. What are all the possible ways to change the resistance of a conductor?

I know the basic three

1. Change the cross sectional area of the conductor
2. Change the length
3. Change the temperature

Are the other ways?

I was thinking that situating the conductor in a magnetic field would cause the charge carriers to bunch on one side of the conductor and change its resistance.

2.

What are all the possible ways to change the resistance of a conductor?

I know the basic three

1. Change the cross sectional area of the conductor
2. Change the length
3. Change the temperature

Are the other ways?

I was thinking that situating the conductor in a magnetic field would cause the charge carriers to bunch on one side of the conductor and change its resistance.
If you increase the frequency, then the self-generated field will cause the conducting electrons to concentrate towards the outer diameter and increase the effective resistance. This effect is taken into consideration in the design of long-distance transmission lines.

4. Ok, makes sense. What you are referring to is called the "skin effect". I know quite a bit about that actually.

So, like you said, if one creates a high frequency current on a conductor J (current density) goes up around the outside of the conductor, which increases the effective resistance.

That's what I was getting at with the hall effect. If the conductor is situated in a magnetic field this will modify J in the conductor and thus change the effective DC resistance.

5. Resistance is an inheirent property of the material and from your list only temperatue has an effect

6. No, Resistivity is an inherent property of a material.

Resistance is different from resistivity.

One could make several conductors that all have the same resistivity but different resistances.

7. :I stand corrected-anyway it is temp dependent

No, Resistivity is an inherent property of a material.

Resistance is different from resistivity.

One could make several conductors that all have the same resistivity but different resistances.
Right.

Other thought. Piezoresistive materials vary resistance with stress.

http://en.wikipedia.org/wiki/Piezoresistive_effect

9. Don't know if this counts, as its a radical change.

Dope the crystal structure of the resistive material so that electrons or holes are in the semi-conduction band ( higher than the valence band ) and are free to move.

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