How is Potential Difference Created across a Resistor?

  • #1
Dario56
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In a simple circuit consisted of a battery and a resistor, how is potential difference actually established on the resistor?

My understanding is that battery creates the electric field which propagates through space at the speed of light. Resistor is put inside this field and therefore potential difference exists on that resistor (as potential difference is just the line integral of the electric field), causing current according to Ohm's law.

However, I also know that potential difference on resistors are established through charges on the conductor surface.

I'm not sure how to connect these two views as in the former case it seems that potential difference is simply created by the electric field of the battery (in the same way how voltage exist between two points in the electric field of the single charge, supposing that two points have a different distance from that charge) while in the latter case there is a charge redistribution on the conductor surface creating that potential difference the resistor.

In another words, in the former case, potential difference has nothing to do with surface charges and their redistribution while in the latter case that holds.

Therefore, according to my understanding, these two views aren't supporting each other. What am I missing?
 
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  • #3
What a great paper! If now he'd also have added the full calculation with the magnetic field and drawing also the Poynting vector describing the energy flow! Then I'd force all my colleagues in the physics-didactics institute to read it carefully! May be they think over their nonsensical "water analogy" for circuit theory, which they hammer into the heads of the teacher students I try to teach Maxwell electrodynamics in their theoretical-physics lecture course :-(.
 
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  • #4
Dale said:
You are right, the connection between these two is not obvious at all. This is the best paper I know for addressing this concept

Rainer Muller. A semiquantitative treatment of surface charges in DC circuits.

https://www.tu-braunschweig.de/inde...oken=2cc8a71e4fdbf159121c6b8ef8348952a2e0c197
Thank you, Dale. I remember when I first found this paper and how much I liked it. It seems that the gap is bridged by the non-stationary state where the initial electric field created by the battery is changed by the local charge redistribution on different interfaces. This redistribution changes the electric field as long as the charge accumulation at all points inside the conductor becomes zero, ##\frac {\partial c}{\partial t} = - \nabla \cdot j =0##. Stationary state is reached, current inside the different conductors in serial connection (branch) is the same.
 
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  • #5
Yes. Note that during that non-stationary state you cannot use circuit theory as it violates the assumptions of circuit theory.
 
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1. What is a resistor?

A resistor is an electronic component that is designed to resist the flow of electric current. It is typically made of a material with high resistance, such as carbon or metal, and is used to control the amount of current flowing in a circuit.

2. How is potential difference created across a resistor?

Potential difference, also known as voltage, is created across a resistor when an electric current flows through it. This is because the resistance of the material in the resistor causes a drop in voltage, which creates a difference in potential between the two ends of the resistor.

3. What factors affect the potential difference across a resistor?

The potential difference across a resistor is affected by the amount of current flowing through it, the resistance of the material in the resistor, and the voltage of the power source. These factors are all related through Ohm's law, which states that the potential difference is equal to the current multiplied by the resistance.

4. How is the resistance of a resistor determined?

The resistance of a resistor is determined by its physical properties, such as the type of material it is made of, its length, and its cross-sectional area. These properties can be measured and used to calculate the resistance using Ohm's law.

5. Can the potential difference across a resistor be changed?

Yes, the potential difference across a resistor can be changed by altering the amount of current flowing through it or by changing the resistance of the resistor. This can be done by using different materials or by adjusting the physical properties of the resistor.

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