Zašto radio talasi prolaze kroz zidove, a svetlost ne može?

Ne radi se tu samo o energiji fotona koja je dovoljna ili nedovoljna da izbaci elektron iz atoma, vec ima i drugih procesa koji se tu desavaju. Recimo foton moze da interaguje sa atomom zida tako sto biva apsorbovan a energija fotona se trosi na zagrevanje (npr. povecanje amplitude oscilovanja u kristalnoj resetci) pri cemu se ni jedan elektron ne izbija. Takodje moze doci do reflektovanja. Osim toga nije pravilo da fotoni nize energije prolaze kroz prepreke a fotoni vise energije se odbijaju ili reflektuju. Primer? Gama zraci prolaze kroz zid (osim ako nije od olova). Takodje infracrveni deo spektra (manje energije od vidljive svetlosti) ne prolazi kroz staklo (kvarc).

Intezitet EM zracenja opada eksponencijalno po Ber-Lamberovom zakonu (http://en.wikipedia.org/wiki/Beer–Lambert_law) sto bi teoretski znacilo da bi dovoljno jak izvor vidljive svetlosti mogao da prodje kroz zid proizvoljne duzine.

Interakcija EM talasa sa materijom je jedna velika oblast u fizici i mislim da nije moguce opisati na opstem nivou sta se desava sa svakim pojedinacnim slucajem. Svaki materijal ima svoje karakteristicne osobine koje odredjuju oblasti EM zracenja koje su za njega transparentne odnosno apsorpcione/reflektujuce. Ipak evo ovde ima jedan zadovoljavajuc odgovor na tvoje pitanje:

Citat:

The reason why visible light can't travel through walls as easily as gamma rays or radio waves is because, to the visible light, there's something 'there' on a similar scale of length (wavelength) and time (frequency) that the gamma rays are too small and fast to interact with and the radio waves are too large and slow to interact with.

The gamma rays just pass through the spaces between and within atoms and molecules. They're small enough to do that. If your walls were made of pure lead, they'd have a little more trouble.

The radio waves on the other hand are large enough to ignore the walls because they're too thin. But if you've ever tried to listen to a radio in a tunnel or a cave, you know that radio waves have trouble penetrating through meters of earth.

Visible light interacts with many solid materials because the wavelengths are the right size to be scattered by structural elements within those materials like microfibers and cracks and porous spaces. Well-cut glass or diamond don't have these structural elements at this length scale so they look clear unless they're shattered or rough.

So scattering due to physical elements of the right size is a major reason, but another factor contributes too.

http://www.physlink.com/Educat...A51-15C5-EE01-B912029FFB4AE647

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