Dismiss Notice
Join Physics Forums Today!
The friendliest, high quality science and math community on the planet! Everyone who loves science is here!

How Data on electromagnetic waves are transmitted ?

  1. Aug 7, 2011 #1
    Hello every one .
    We know Radio waves carrying data
    When a radio device receives radio waves , It render the waves and we hear sound .

    Now my questions are :
    1 - How data on electromagnetic waves are transmitted ?

    When a electromagnetic wave hit a atom it absorbed by the atom
    like this

    Then after a short delay another photon is emitted .

    2 - What happens to the data at this moment ?

    3 - What's the data ? are they atoms ? are they electrons ? are they Community atoms ? or ...... ?
  2. jcsd
  3. Aug 7, 2011 #2


    User Avatar
    Staff Emeritus
    Science Advisor
    Education Advisor

    Er.. you have a wrong idea on basic E&M, especially on antenna.

    Since EM waves (photons) have oscillating E-field, I can detect such waves simply with an antenna. That's what your radio does. One can naively think of it as the oscillating E-field inducing current in an antenna. This current is the transmitted signal. What you are receiving is not due to some atomic excitation.

  4. Aug 7, 2011 #3


    User Avatar
    Staff Emeritus
    Science Advisor
    Homework Helper

    To find out how sound information is sent by radio, search about "amplitude modulation" or "frequency modulation", better known as AM and FM.
  5. Aug 8, 2011 #4
    One could almost think of an old player piano where little bumps at different places make different sounds. You could think of different amplitudes or wavelengths as changing the location of the bump on the roll.
  6. Aug 8, 2011 #5


    User Avatar
    Staff Emeritus
    Science Advisor

    Look up antenna, AM and FM radio, electromagnetic radiation, and other similar items on wikipedia. That will explain pretty much everything about this.
Share this great discussion with others via Reddit, Google+, Twitter, or Facebook