Energy of a charge configuration

In summary, the conversation discusses the issue of energy being missing in the process of assembling a charge configuration due to the radiation of particles. The solution to this problem is to bring in the charges slowly and steadily, as it is a thought experiment and not a practical method. The energy released in this process is represented by the Poynting vector, and the key to understanding it is to consider the energy of the charge configuration rather than the radiated energy.
  • #1
zwoodrow
34
0
Im rereading griffiths electrodynamics and noticed all the derivations of energy to assemble a given charge config assume you can bring charges in from infinity and stick them down. In reality if you tried this inevitable some of the particles would accelerate away or towards the incoming charge- they would radiate during acceleration - energy would go missing. How to deal with this.
 
Physics news on Phys.org
  • #2
I don't understand - why do you need to 'deal with it'. It's a mathematical construction - a thought experiment.
It wouldn't be practical to actually assemble a charge configuration that way - you just pointed out why.
 
  • #3
I just answered my own question- the energy released in assemble a charge or current configuration is represented bythe poynting vector.
 
  • #4
A key to the idea, what AJ Bentley is talking about, is that you bring in the charges slowly and steadily such that they don't radiate energy. Its a thought experiment on what determines the energy of a charge configuration, radiated energy has nothing to do with it.
 
  • #5


I would like to point out that the assumptions made in the derivations of energy for assembling a charge configuration are simplifications and idealizations for mathematical convenience. In reality, the process of bringing charges from infinity and assembling them into a specific configuration is not possible without some form of external force or constraints.

The issue of radiation and loss of energy during the process of assembling charges is a valid concern. However, this can be addressed by considering the energy loss due to radiation as a part of the overall energy budget for the system. In other words, the energy required to assemble the charge configuration should also include the energy lost due to radiation.

Furthermore, it is important to note that the radiation from charges during acceleration is a fundamental aspect of electromagnetism and cannot be ignored. In fact, it is this radiation that allows us to observe and study the behavior of charged particles. Therefore, it is not a problem that needs to be "dealt with," but rather a crucial aspect to be considered in any analysis of charge configurations.

Overall, while the assumptions made in derivations may not accurately reflect the real-world scenarios, they serve as useful tools for understanding and predicting the behavior of charge configurations. As scientists, it is our responsibility to acknowledge the limitations of these assumptions and continue to refine our understanding through further research and experimentation.
 

1. What is the definition of energy in a charge configuration?

The energy of a charge configuration is the amount of work required to assemble a collection of charges into their respective positions and orientations in space.

2. How is the energy of a charge configuration calculated?

The energy of a charge configuration can be calculated using the formula E = kq1q2/r, where k is the Coulomb's constant, q1 and q2 are the magnitudes of the two charges, and r is the distance between them.

3. What factors affect the energy of a charge configuration?

The energy of a charge configuration is affected by the magnitude of the charges, the distance between them, and the medium in which the charges are located.

4. How does the energy of a charge configuration change when the distance between the charges is increased?

As the distance between the charges increases, the energy of the charge configuration decreases. This is because the electric force between the charges decreases with distance.

5. Can the energy of a charge configuration be negative?

Yes, the energy of a charge configuration can be negative if the charges have opposite signs. This indicates that work would need to be done to separate the charges and bring them to infinity, which is the reference point for potential energy calculation.

Similar threads

  • Electromagnetism
Replies
14
Views
1K
Replies
6
Views
1K
Replies
21
Views
1K
  • Electromagnetism
Replies
1
Views
655
Replies
2
Views
1K
Replies
7
Views
2K
Replies
4
Views
1K
  • Electromagnetism
Replies
1
Views
1K
Replies
28
Views
3K
Replies
7
Views
1K
Back
Top