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Introduction to electromagnetism - Maxwell's equations

  1. Apr 23, 2010 #1
    Q1) The amplitude of an electromagnetic wave is E0 = 471.0 V/m. Find the following values.
    (a) Erms
    333.047 V/m

    (b) Brms
    __ nT

    (c) the intensity I
    __W/m2

    (d) the radiation pressure Pr
    __nPa


    Q2)(a) For a given distance from a radiating electric dipole, at what angle (expressed as θ and measured from the dipole axis) is the intensity equal to 83 percent of the maximum intensity?

    (b) At what angle θ is the intensity equal to 3 percent of the maximum intensity?




    I'm not sure what the general formulas are.
     
  2. jcsd
  3. Apr 23, 2010 #2

    berkeman

    User Avatar

    Staff: Mentor

    Hint for 1b -- the ratio of E/B is determined by the characteristic impedance of the medium that the EM wave is propagating through.

    And on question 2, you must have learned some things about dipole antenna radiation patterns, or they would not have asked you that question.
     
  4. Apr 23, 2010 #3

    ideasrule

    User Avatar
    Homework Helper

    Here are the general formulas:

    E=Bc
    Energy density=1/2*epsilon*E^2
    Energy density=1/2*B^2/mu

    Dipole formulas: http://en.wikipedia.org/wiki/Dipole_antenna
     
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