How Do Electrons Flow Through Conductive Wires?

In summary: Eddy current losses are also similar.In summary, electrons flow through wires due to collisions and an applied electric field. Thin wires have more resistance because there are fewer electrons and a larger electric field is needed for the same current. The "skin effect" is a result of magnetic forces on moving electrons and is only relevant for high frequency alternating currents. In a curved wire, the current is unevenly distributed with more electrons passing near the center of curvature. The Chemistry model in Quantum Mechanics explains the behavior of electrons in metals. When a metal is curved, there is no significant change in magnetic pull or eddy forces compared to a straight wire.
  • #1
Brock
39
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Is is known exactly how electrons flow through wires? For example a wire is conductive, the air around it is not, and thin wires conduct worse then thick wires, would this mean that the electrons force, or flow is greatest in the centre of the wire? Like water through a pipe?
 
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  • #2
Yes it is very well known. I give you a very short and simplified (but correct) explanation:

In a metal, there are so called "free electrons". There are electrons detached from the atoms (less than one for each atom) that can wander freely in the metal. But, as people in a room, they distribute more or less uniformly over al the room (metal).
All the time there are collisions between the electrons and between the electrons and the atoms. There is equilibrium in the speed of electrons and the agitation of atoms. You said that electrons and atoms are in thermal equilibrium. That is they are at the same temperature.
When you apply a voltage across the metal an electrical field appears and this electrical field pushes the electrons to the positive end. This push changes slightly the speed of electrons in the good direction. As the electrons gain speed they gain temperature and in the chocks with atoms they loss temperature and heat the atoms.
This is the resistance: the electrons lose the gained energy, giving it to the atoms. To have a current, you must provide an electric field, plus energy and this energy heats the metal.
Thin wire conduct worse than thick ones not of friction with the surface of the wire, as do water in a pipe. In a thin wire there are fewer electrons and to obtain the same current you must give them more speed. This asks for bigger electric field and gives bigger loses (heat).
 
  • #3
It might also be mentioned that electrons repel each other, causing a "skin-effect" to occur with respect to electron distribution in a live conductor.
 
  • #4
pallidin said:
It might also be mentioned that electrons repel each other, causing a "skin-effect" to occur with respect to electron distribution in a live conductor.

When giving an explanation it is better to avoid mentioning irrelevant subjects.
Electrons do repel each other (I said " But, as people in a room, they distribute more or less uniformly over all the room (metal).").
Anyhow, as electrons move in a sea of fixed positive charges (atoms which have lose an electron), essentially, they do not "see" the others electrons.
Then repulsion between electrons is mostly irrelevant to metallic conduction.
The "skin effect" has nothing to do with electron repulsion. It is due to magnetic forces exerted on moving electrons by the magnetic field created by the current. It is only relevant for alternating currents and at frequencies bigger than 1 or 2 tens of kilohertz.
 
  • #5
Ok, so they flow through a typical wire evenly spread out, from centre to outside?

What happens when the wire is curved? Does the Tesla coil Lower amps, and raise voltage?
 
  • #6
Brock said:
Ok, so they flow through a typical wire evenly spread out, from centre to outside?
Yes.

Brock said:
What happens when the wire is curved?
The current "takes the bend" and more electrons pass at the side of the wire near the center of curvature than at the opposite outer side. The dependence is of the type 1/R, where R is the radius of the trajectory.

Brock said:
Does the Tesla coil Lower amps, and raise voltage?
Tesla coil is just a transformer. But the Tesla coils that you see in labs and technical museums
work at high frequencies (20 -50 kHz), and have very high transformation ratios. They output tens of thousand of volts that are no very dangerous because of the "skin effect" at these frequencies.
 
  • #7
do you know if any changes happening in the electron orbitals of the wire's atoms? does a coil of Iron wire have more magnetic pull, and eddy force then a coil of copper wire? Since if you put an iron rod in a copper coil it's more magnetic then the copper coil alone.
 
  • #8
There is a "skin" effect with high frequency AC.
 
  • #9
Indeed, in Chemistry and even in Physics it's well known. However, the Chemistry model in Quantum Mechanics really explains it well.

Water is an alright model to compare it to, but that breaks down real quick.
 
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  • #10
AngeloG are you reponding to my first post, and agreeing that it flows faster in the centre of the wire? And can you explain the Chemistry model in Quantum Mechanics in more detail?
 
  • #11
Brock said:
do you know if any changes happening in the electron orbitals of the wire's atoms?.

The orbitals of last electrons "touch". In fact the orbitals do not stop abruptly but fade rapidly with distance. The consequence is that these electrons can tunnel very easily form atom to atom (and become free electrons). The energy states of these coupled orbitals degenerate and gives a very big number of states with energies distributed in a few electron-volts gap. This is what is called the "conduction band".

Brock said:
do you know if any changes happening in the electron orbitals of the wire's atoms? does a coil of Iron wire have more magnetic pull, and eddy force then a coil of copper wire? Since if you put an iron rod in a copper coil it's more magnetic then the copper coil alone.
No. Magnetic field will be almost the same (there may be a very minor and insignificant difference).
 

What is electricity and how does it flow through wires?

Electricity is the flow of electric charge through a conductor, such as a wire. It is the movement of electrons from one atom to another. This flow of electrons creates a current, which is what powers electrical devices. In order for electricity to flow through wires, there must be a complete circuit with a power source, such as a battery or outlet, and a path for the current to travel.

What is the difference between AC and DC current?

AC (alternating current) and DC (direct current) are two types of electric current. AC current periodically changes direction, while DC current flows in one direction. AC current is used for most household electricity, while DC is commonly used in batteries and small electronics. Electricity from power plants is converted to AC current before being distributed through power lines, while batteries provide DC current directly.

Why do wires have different colors?

The color of wires is used to indicate their function in a circuit. In most cases, black wires are used for hot or live wires, white wires for neutral wires, and green or bare wires for ground wires. Other colors, such as red, blue, and yellow, may be used to indicate specific functions, such as a switch or a three-way wire. These color codes are important for proper installation and safety.

How is electricity measured?

Electricity is measured in units called watts (W) or kilowatts (kW). One watt is equal to one joule of energy per second. Kilowatts are used to measure larger amounts of electricity, such as household energy usage. Another unit of measurement for electricity is amperes (A), which is a measure of the amount of current flowing through a circuit. Voltage (V) is also important in measuring electricity, as it is the force that drives the current through a circuit.

What are some safety precautions for working with electricity and wires?

Working with electricity can be dangerous, so it is important to take proper safety precautions. Always turn off the power source before working with any wires. Use insulated tools and wear protective gear, such as gloves and goggles. Be aware of where wires are located and avoid touching them. Make sure all wires and connections are secure and not damaged. If you are unsure or uncomfortable working with electricity, it is best to consult a professional.

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