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Couple of Questions Regarding EM Waves

  1. Apr 21, 2013 #1
    I'm a little unsure of my own answers to these questions. Hopefully I'll clear up my misconceptions.

    1. If I measure the E-field and B-field at a point in space where there is an EM wave, would I be able to determine the direction it propagates from?

    My Ans: I don't think so, since when you do a reading a a point, you only get the scalar value

    2. If a point charge +q lies on the x-axis and is in the path of a sinousoidal EM wave, will the point charge move?

    My Ans: I believe it would just oscillate at that point

    3. Most vehicles have got upright and vertical receiving antennas. What does this tell about the E-field polarization of the radio waves that are being broadcasted?

    My Ans: It is vertical.

    4. Does electromagnetic standing waves have energy? Does it have momentum?

    My Ans: Yes. Yes

    Could anyone go through my answers and let me know if I have any misconceptions?
  2. jcsd
  3. Apr 21, 2013 #2
    The field is a vector, if you measure it at any point it will still be a vector, if you measure the field at a point you will know about the field at that point, if you also know that the field is monochromatic you will know which direction it is headed towards.
    Yes the point charge will experience a force.
    Yes as long as the cross product between the E and B fields is non-zero there will be field momentum, all foelds on the other hand have energy.
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