penetration of em spectrum's

Discussion in 'Wireless & RF Design' started by bhuvanesh, Jun 18, 2014.

  1. bhuvanesh

    Thread Starter Member

    Aug 10, 2013
    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
  2. Papabravo


    Feb 24, 2006
    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.
  3. MrChips


    Oct 2, 2009
    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.
  4. sirch2

    Well-Known Member

    Jan 21, 2013
    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
  5. Alec_t

    AAC Fanatic!

    Sep 17, 2013
    They can. Many substances are transparent or translucent at optical wavelengths.
  6. MrChips


    Oct 2, 2009
    Glass is highly transparent at optical wavelengths.

    Think about it for a second.
  7. alfacliff

    Well-Known Member

    Dec 13, 2013
    and lexan is transparent at optical frequencies, but not at infrared.
  8. nsaspook

    AAC Fanatic!

    Aug 27, 2009
    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.
    Last edited: Jun 18, 2014