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Homework Help: Wave equation

  1. Apr 3, 2013 #1
    I have come back to studying physics after 5 years and I'm doing a course in electromagnetism.

    I've come to the wave equation and I'm a little rusty.

    For example, the general solution,

    A(z,t) = Acos(2*pi*z/L - 2*pi*f*t + phi)

    I know basically what the terms mean, but I'm unsure how they work together to form the wave, and can't seem to form an intuitive picture in my head.

    My exam is in 3 weeks, do I need to figure this out quickly. I find it near impossible to move on if I don't understand something like this.
  2. jcsd
  3. Apr 3, 2013 #2
    In the last paragraph, it should be "so" not "do" :)
  4. Apr 3, 2013 #3
    A is the amplitude of the wave. Basically meaning the maximum values that the wave can reach.

    2*pi/L is the wave number, k, where L is the wavelength. This takes your position and tells you where you are on the wave

    2*pi*f is the angular frequency, omega, where f is the frequency. This takes your time and tells you where you are on the wave.

    Phi is the phase angle. This tells you if your wave has been shifted at all. A phase angle of 0, 2pi, 4pi, etc will give you constructive interference between waves and a phase angle of pi, 3pi/2, etc will give you destructive interference

    Notice how the units of z and L cancel out, as do the units of f and t

    I hope that these make sense. And note that I'm still studying in undergrad so these might not be all right or accurate to the degree you were hoping for
  5. Apr 3, 2013 #4
    Hey, thanks for replying.

    I understand what you said, and this is basically what it says in my textbook.

    I'm going to go away and have a think about this while I'm at work tomorrow. I'll also try and find some kind of web applet to help me visualise it.

    I'll post it on here if I find a good one.
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