Energy transfer in electricity conduction

In summary, the mechanism of energy transport when electricity is conducted through a conductor is similar to the gravitational potential energy in that the source of energy comes from the power supply, the electric field causes the electrons to do work, and the resulting energy can be converted to other forms. In a conductor, the electrons do collide with the ions in the crystal lattice, causing them to drift sideways under the influence of the applied electric field. The energy released in conduction comes from the field, and is absorbed by the material, similar to how a body under the influence of a gravitational field reaches a terminal velocity and all the energy provided is used to heat the body and air. However, in an ideal conductor, the electric field is zero, while in a
  • #1
loom91
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Hi,

I was wondering something. What is the mechanism of energy transport when electricity is conducted through a conductor? The continuity equation requires current to be constant in a circuit, which means the expectation velocity of the electrons in the conduction bands must be constant throughout the circuit, no kinetic energy is lost. Yet resistances in the circuit get heated. Where does this energy come from?

Thanks.

Molu
 
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  • #2
I am not on your level, but it might be helpfull to compare the situation with its gravitational equivalent. The source of gravitational potential energy is our planet (power supply). It generates a force (electric) field that causes the object (electric charge) to do work when moved by the field. The resulting energy can be converted to other forms (heat), depending on what the object encounters on its way through the field.

Having said that I must confess that logic brought me to the conclusion at some stage that there should not be an electric field in a good conductor.
 
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  • #3
But under a gravitational field changes in kinetic energy occur. Also, why do electrons have constant velocity in a conductor? Should not they be accelerated? Thanks.
 
  • #4
In a conductor the free electrons do collide with the ions (that lost the electrons) in the crystal lattice at regular intervals on the average. When an electric field is applied the electron paths become slightly curved between the collisions, that is the electrons are pushed sideways a bit. This means that the electrons do accelerate between collisions, but they lose their gained speed again due to the collisions. So on the average all that happens to the path of the electrons due to the applied electric field is that they drift sideways a bit under its influence.
 

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But where does the energy released in conduction come from? The average kinetic energy of the electrons is staying the same, so what energy translates into the vibrational energy of the resistance? Thanks.

Molu
 
  • #6
Can anyone help me?
 
  • #7
loom91 said:
But where does the energy released in conduction come from? The average kinetic energy of the electrons is staying the same, so what energy translates into the vibrational energy of the resistance? Thanks.

Molu

The energy comes from the field. If there were no collisions with the ions, the electrons would accelerate indefinitely. In the collisions they lose their kinectic energy that is transferred to the ions, which vibrate with higher amplitude. In the steady state, all the energy provided by the field is absorbed by the material.
The gravitational analogy is valid if there is air present. A body under the influence of the gravitational field accelerates until it reaches terminal velocity. Then the velocity is constant and all the energy provided by the gravitational field is used to heat the body and the air.
 
  • #8
But what of the theorem that electric field is zero inside conductor? Thank you.

Molu
 
  • #9
loom91 said:
But what of the theorem that electric field is zero inside conductor? Thank you.

Molu
The electric field is zero inside an ideal conductor. In this case there is no resistance and no dissipated power and the voltage at the extremes of the conductor is zero.
In a real conductor you need a potential difference at the extremes of the conductor in order to establish a current, so there is a nonzero field.
 

1. How does energy transfer occur in electricity conduction?

Energy transfer in electricity conduction occurs through the movement of electrons. When a source of electricity, such as a battery, is connected to a conductor, such as a wire, the electrons in the conductor begin to move in a specific direction. This movement of electrons is known as an electric current, and it is the transfer of energy from the source to the conductor.

2. What factors affect energy transfer in electricity conduction?

There are several factors that can affect energy transfer in electricity conduction. These include the material of the conductor, the temperature of the conductor, the length and thickness of the conductor, and the voltage of the electricity source. A material with higher conductivity, such as copper, will have better energy transfer compared to a material with lower conductivity, such as rubber.

3. How is energy lost during electricity conduction?

Energy can be lost during electricity conduction due to resistance. Resistance is a natural property of materials that impedes the flow of electrons. As electrons move through a conductor, they encounter resistance, which causes some of the energy to be converted into heat. This is why wires can become hot when electricity is passing through them. The longer the wire, the higher the resistance, and the more energy will be lost.

4. Can energy transfer in electricity conduction be improved?

Yes, there are ways to improve energy transfer in electricity conduction. One way is to use materials with higher conductivity, as mentioned before. Another way is to reduce the length of the conductor, which will decrease the amount of resistance encountered by the electrons. Additionally, using thicker wires can also improve energy transfer since they have a lower resistance compared to thinner wires.

5. How is energy transfer in electricity conduction measured?

The unit used to measure energy transfer in electricity conduction is called the watt. One watt is equal to one joule of energy transferred per second. The amount of energy transferred can also be measured using a device called an ammeter, which measures the electric current in a circuit. By multiplying the current by the voltage, the amount of energy transferred can be calculated.

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