Electromagnetic radiation (EMR) threshold

In summary, the transition from near field to far field in an electromagnetic field does not have a specific threshold energy or frequency. As the distance from the source increases, the near-field portion of the field diminishes rapidly and the far-field portion becomes dominant. This shift typically occurs when the distance reaches a few wavelengths from the source. This transition is not constant and depends on the distance from the source.
  • #1
Homestar1
16
2
What is the threshold energy (or frequency) required for an electromagnetic field to transition from a near field to become self propagating (EMR), far field? (If I'm using the right definitions to ask the question correctly). Is this constant or are there other details needed to calculate this?
 
Physics news on Phys.org
  • #2
There is no threshold. Given some distance from the source, some portion of the field will be near-field and some will be far-field, with the near-field falling off extremely rapidly as distance increases. Once the distance is more than a few wavelengths, there is virtually no near-field left.
 
  • Like
Likes PeroK
  • #3
Ah, that makes sense! Thanks so much!
 

1. What is electromagnetic radiation (EMR) threshold?

The electromagnetic radiation (EMR) threshold is the level of exposure to electromagnetic radiation that is considered safe for humans. It is the maximum amount of radiation that can be absorbed by the body without causing harm.

2. How is the EMR threshold determined?

The EMR threshold is determined through extensive research and studies conducted by scientists and regulatory agencies. They take into account factors such as frequency, intensity, and duration of exposure to determine safe levels of EMR.

3. What are the potential health effects of exceeding the EMR threshold?

Exceeding the EMR threshold can lead to a variety of health effects, including skin burns, tissue damage, and increased risk of cancer. It can also cause interference with the body's natural electrical signals, leading to disruptions in bodily functions.

4. Is there a universal EMR threshold for all types of radiation?

No, the EMR threshold varies depending on the type of radiation. For example, the threshold for ionizing radiation (such as X-rays and gamma rays) is much lower than non-ionizing radiation (such as radio waves and microwaves).

5. How can we protect ourselves from exceeding the EMR threshold?

To protect ourselves from exceeding the EMR threshold, we can limit our exposure to sources of radiation, such as electronic devices and appliances. We can also use protective measures, such as shielding materials, to reduce our exposure to EMR.

Similar threads

Replies
6
Views
772
  • Electromagnetism
Replies
4
Views
985
Replies
1
Views
1K
  • Electrical Engineering
Replies
7
Views
216
  • Atomic and Condensed Matter
Replies
19
Views
2K
  • STEM Educators and Teaching
2
Replies
39
Views
5K
  • Classical Physics
Replies
3
Views
223
  • Electromagnetism
Replies
8
Views
2K
Replies
9
Views
2K
  • Electromagnetism
Replies
2
Views
79
Back
Top