Gamma/Radio waves through solids

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Discussion Overview

The discussion revolves around the transmission of gamma and radio waves through solids compared to visible light, exploring the reasons behind their differing interactions with materials. Participants examine the nature of electromagnetic (EM) wave interactions, the role of electron movement, and the implications of wavelength on absorption and transmission.

Discussion Character

  • Exploratory
  • Technical explanation
  • Conceptual clarification
  • Debate/contested

Main Points Raised

  • Some participants suggest that the different wavelengths of gamma and radio waves compared to visible light affect their interactions with materials, potentially allowing them to pass through more easily.
  • One participant references a paper discussing the behavior of photons in matter, noting that high-energy gamma rays can produce electrons and positrons when interacting with protons.
  • Another participant points out that EM waves interact with matter primarily through electrons, with the degree of interaction depending on the material's properties, such as whether electrons are free or bound.
  • It is mentioned that longer wavelengths, like radio waves, can penetrate materials like thin sheet metal more effectively than visible light.
  • A participant questions the effectiveness of radio waves when wrapped in aluminum foil, leading to a discussion about the frequency of modern communication devices.
  • Some participants explore analogies between the transmission of EM waves through materials and sound waves propagating through a medium, with varying degrees of agreement on the validity of these analogies.

Areas of Agreement / Disagreement

Participants express a range of views on the interactions of EM waves with materials, with no clear consensus on the specifics of these interactions or the effectiveness of analogies drawn between different types of wave propagation.

Contextual Notes

Participants note that the behavior of EM waves in materials can be complex and dependent on various factors, including the nature of the materials and the specific wavelengths involved. Some claims are based on simplified models, while others acknowledge the need for empirical measurements.

Who May Find This Useful

This discussion may be of interest to those studying electromagnetism, materials science, or anyone curious about the properties of different types of electromagnetic radiation and their interactions with matter.

Infrasound
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Why is it that gamma and radio waves can pass through some solids so easily compared to visible light? I understand that the wavelengths are different than visible light, but why does that effect things?

Do they simply not interact with anything in the material? Or, if they do, what to they interact with?

Also, do they change speed when traveling through the material. I guess that question depends on the second.
 
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This paper talks about shooting all kinds of photons through matter .
http://pdg.lbl.gov/2009/reviews/rpp2...les-matter.pdf
Bob S showed me this ,
And also you can shoot high-energy gamma rays at some material and when they scatter off protons they can produce electrons and positrons .
 
Last edited by a moderator:
EM waves interact with matter primarily through interaction with electrons.

In some materials, (some of the ) electrons are fairly free to move - conductors for example. In those, the energy of the radiation is absorbed exponentially with depth according to the wavelength. Longer wavelengths which only move the electrons slowly are able to pass through fairly easily - radio waves can go through thin sheet metal, light can't.

In other materials, the electrons are bound to atoms but can still move to some extent although the ways they can vibrate are restricted - that leads to selective absorption and reflection depending on frequency - different colours, different transparencies etc.
This will depend in a very complex way on the exact nature of the molecules involved.
In some simple cases we can make predictions (Compton scattering for example), in many we can only make measurements and produce tables of behaviours.
 
AJ Bentley said:
- radio waves can go through thin sheet metal, light can't.

Then how come when i wrap my cell phone in aluminum foil it can't get the call .
 
Modern comms devices use ultra-high frequency radio waves. An old-fashioned valve radio picking up the light program on 200kHz wouldn't even notice.
 
Can the transmission process (through a material) be thought of as analogous to sound waves propagating through a medium, where one particle gives the energy to the next? Only with electrons as opposed to whole molecules.

Then, absorption analogous to the disorganized transfer of energy in a lattice?

Then, reflection, similar to resonant surface reflection?

Sorry, my brain always tries to take these things and run with them, which is sometimes wrong.
 
Infrasound said:
Can the transmission process (through a material) be thought of as analogous to sound waves propagating through a medium

More or less - a reasonable analogy.
 

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