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I have read answers stating that light is not able to be transmitted through a wall whereas sound is easily transmitted due to difference in wavelength. But, why? I am looking for detailed and satisfactory answer. Please also include the reason of WIFI signals easily transmitting through any media as compared to sound.

N A McMahon
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Vivek Gupta
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  • What do you mean "difference in wavelength"? Sound and visible light are more different than merely having different wavelengths! What research have you done to answer this question? – ACuriousMind Nov 27 '17 at 13:29
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    This question (v3) must be a duplicate. – Qmechanic Nov 27 '17 at 13:44
  • See https://physics.stackexchange.com/q/300551/ for a comparison of visible EM versus Wifi EM transmission. – Bill N Nov 27 '17 at 16:57
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    There are walls which transmit visible light much better than they transmit sound. They are usually made of glass or acrylic plastic. Your question is not well-posed. Specific materials have specific properties. There are some materials which transmit (humanly) visible but not UV. Others transmit IR but not visible. And as @ACuriousMind points out, sound and EM waves are similar only in that they transmit energy from point A to point B, and they have similar mathematical functions. The actual mechanisms of production and propagation are radically different. – Bill N Nov 27 '17 at 17:03
  • -1 No research effort. I googled your title and the above Physics SE question was returned as the #1 hit. – sammy gerbil Nov 27 '17 at 19:10

1 Answers1

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The walls parameters

A wall has a thickness and is made from specific material. Depending from this parameters you get different results for sound and light:

  1. For (window) glass it’s obvious that rather light is going through then sound.
  2. For a sheet of paper mainly both sound and light are going through.

The light parameters

Light is the visible part of the electromagnetic spectrum. X-rays are also part of the EM radiation as well as microwaves. Both radiations are going through room walls. To say it a little bit simplified, the EM radiation, which is going through walls, depends from the energy content of the photons (X-ray) as well as from the wavelength of the photons (microwaves or cm-waves).

The nature of sound and light

  1. Sound is the perturbation of the molecules of a gas or a solid or a liquid. Coming to your ear the change in gas pressure makes you listen sound.

  2. Light is emitted and get received in packages, called photons. Photons are traveling in empty space. Hitting the atoms in an obstacle they get reflected or absorbed and re-emitted. This depends from the wavelength of the light and the material of the wall.

The WiFi-signal could be stopped by sputtered glass, it will be reflected meanwhile light is going through.

HolgerFiedler
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