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Amplitude of oscillating magnetic field

  1. Jun 20, 2012 #1
    N = 1/2 E0 √(ε/μ)
    so
    E0 = √2*N*(ε/μ)
    where the value of ε/μ is 376.7Ω

    I have a similar question to this, below, regarding amplitude of an oscillating magnetic field.
    Yes, I'd like the answer, but am initially stuck deciding whether the mW is milli- or mega-

    2. Relevant equations
    A laser found in supermarket checkout scanners emits light in a 1.1 mm diameter beam with a power of 1.3 mW.

    Part A
    What is the amplitude of the oscillating electric field in the laser beam?
    Express your answer to two significant figures and include the appropriate units.
    =

    Part B
    What is the amplitude of the oscillating magnetic field in the laser beam?
    Express your answer to two significant figures and include the appropriate units



    Part A
    N = 1/2 E0 √(ε/μ)
    so
    E0 = √2*N*(ε/μ)
    where the value of ε/μ is 376.7Ω
    E0 = √2*103*376.7Ω
    = 877.0 V m-2

    Not sure how to find the amplitude of the oscillating magnetic field though.

    Any help gratefully received.
     
  2. jcsd
  3. Jun 22, 2012 #2

    BruceW

    User Avatar
    Homework Helper

    I'm not sure what N is supposed to mean? Also you've written: "where the value of ε/μ is 376.7Ω" But that should have units of ohm squared.
     
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