penetration of em spectrum's

Thread Starter

bhuvanesh

Joined Aug 10, 2013
268
x rays are left to visible light and radio waves are right.Both can penetrate but why visible rays cant.what property of waves effect the penetration power(is it like wave length frequency like that).answer me basically plzzz
 

Papabravo

Joined Feb 24, 2006
21,225
All EM waves will do one of several things when encountering different materials and substances.
  1. They will pass through.
  2. They will be reflected.
  3. They will be refracted.
What happens depends on the wavelength(frequency) of the wave and the properties of the material.

I don't understand the meaning of:
x rays are left to visible light and radio waves are right.
 

MrChips

Joined Oct 2, 2009
30,810
x rays are left to visible light and radio waves are right.
This is not a useful way of differentiating the characteristics of EM waves. Obviously you are referring to a diagram of EM radiation with respect to its wavelength.

The orientation would be reversed with reference to frequency.
 

sirch2

Joined Jan 21, 2013
1,037
In general the lower he frequency the further it penetrates (e.g. VLF for submarine comms). XRays break this rule for short range because they carry a lot of enery and in the classic xray image they penetrate flesh but not bone. However a sufficiently bright light can be seen though soft tissue. If fact we all did it as a child, put your hand over a bright torch (flashlight for our US cousins) in a darkened room
 

nsaspook

Joined Aug 27, 2009
13,277
What determines (simplified) the optical properties in classical EM theory is the 'current' flow in the material as a result of the EM wave hitting the material at the boundary of another material. This can be a conduction current in metals (that can reflect the energy in a good conductor,The wave does not penetrate into the conductor due to total internal reflection), resistance(that will absorb the energy has heat)/skin effect(that decreases conductivity as the frequency increases reducing reflection) or a 'displacement' current in a insulator like glass or Lexan that have atomic, molecular or lattice vibrational modes at a frequency or bands of frequencies that differs from the 'displacement' current of vacuum per Maxwell. There are dielectric losses and non-linearities that reduce or distort the energy in various ways as it passes in the material.

This change in 'current' in the material slows the speed of light in the material causing a phase shift of the wavefront altering its path like a mower moving from sidewalk to grass.



If this 'phase shift' or incident angle is increased we can have total internal reflection at the angle of refraction of 90º.
 
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