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Light wave travelled?

  1. Mar 8, 2005 #1
    In my poor knowledge, wave is created by a disturbance and meanwhile the particle just move upward or downward in a transverse wave . However , light seems a different one . It is move! can anyone explain it for me please?
  2. jcsd
  3. Mar 8, 2005 #2


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    I must admit, I don't quite understand why you find this unusual. You have heard of sounds from far away sources, haven't you? Sound is a wave, which is caused by the vibration of air (or any medium) molecules. But do you think the same air molecules that were vibrating at the source are the identical ones that eventually hit your ear drums? They are not. The air molecules need not have any average displacement. Yet, sound DOES move from one location to another!

    It looks like light isn't that different after all IF we just consider this aspect of it.

  4. Mar 8, 2005 #3
    As ZapperZ said, sound waves are caused by vibration of the air. Even though the air affected by the wave moves only a little, the wave still moves through the air. Light moves in a similar fashion (but not exactly, it does not require vibration of the air and can occur in a vacuum) because it exhibits both properties of particles and waves.
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