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The collimated parallel beam of a LASER

  1. May 4, 2017 #1
    1. The problem statement, all variables and given/known data
    Multiple-choice question:
    The LASER beam is a collimated parallel one, that means that its photons have the same.......
    (i) phase (ii) direction (iii) intensity (iv) frequency

    Attempt at a solution
    I would exclude frequency because it has nothing to do with the fact that LASER beam propagates as collimated beam. I would also exclude intensity too because...I don't know actually, but I don't think it is the correct answer.
    But both the direction and the phase are good reasons why LASER propagates as a collimated parallel beam, but I should choose only one, so please help me!
  2. jcsd
  3. May 4, 2017 #2


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  4. May 4, 2017 #3


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    Staff: Mentor

    You can collimate the light of every light source.

    It depends on how you pronounce the sentence I guess. If you highlight laser, then the phase is the important point, if you highlight collimated parallel beam (more natural I think), then it is the direction.
  5. May 5, 2017 #4
    I think it is the direction, right?
    I study LASER in my course, and by studying it I came to the concept of "collimated parallel beam". So, which choice would be more suitable for this question?
  6. May 5, 2017 #5


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    Staff: Mentor

    I would pick direction. If the format allows it, add a comment that the coherence in phase is given by the fact that it is a laser beam.
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