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Sinusoidal alternating current/Homework

  1. Feb 17, 2015 #1
    Hello everyone thanks for giving me your support, sorry if i post in the wrong section.

    1. The problem statement, all variables and given/known data

    What the problem asks for:
    In the picture we can see the graph of sinusoidal i1=i1(t) and i2=i2(t)
    It asks for:
    ν(as i read, it said only one so that's how i went beyond on resolving ecuations)=?
    φ0=?
    i1(t1)=?
    i2(t2)=?
    φ1=?
    φ2=?
    i hope i translate good, phase shifts φ1221 of i2 behind and before of i1
    Given data:
    t1=2,5×10-3(s)
    t2=5×10-3(s)
    T2=0,02
    Imax1=1,5(A)
    Imax2=1
    http://postimg.org/image/jejwzmzn7/ [Broken] (this is the graph)
    The attempt at a solution
    This is what i did i got stuck at phase shifts.

    i(t)=Imaxsin(ωt+φ)

    1.i(t1)=Imax1sin(ωt11)
    2.i(t2)=Imax2sin(ω22)
    ω=2π/T or 2πv
    ν=1/T=> ν=1/T2=>ν=1/2×10-2(s)-1
    from here => i(t) becomes
    1.i(t1)=Imax1sin(2π/T1t11)
    2.i(t2)=Imax2sin(2π/T2t22)
    from here => φ2 i got it out like this:
    Δt.........Δφ
    T...........2π
    => Δφ=(Δt×2π)/T =>2 φ20=(t2-t1×2π)/T
    => φ2=(5×10-3-2,5×10-3×2π)/T
    =>φ2=(2,5×10-3×2π)/1/2×10-2
    =>φ2=5×10-5×2π
    so
    2.i(t2)=Imax2sin(2π/T2t22)
    i(t2)=sin(2π×1/2×10-2×5×10-3+5×10-5×2π)
    after this i said that
    T1 =t2-t1+T2
    => (2,5×10-3+2×10-2
    =>(4,5×10-5)
    which got me confused cause if this is different from the other one(T2).... then shouldn't it have to v?
     

    Attached Files:

    Last edited by a moderator: May 7, 2017
  2. jcsd
  3. Feb 17, 2015 #2

    lightgrav

    User Avatar
    Homework Helper

    If they want 2 distinct φ values, that means one for each curve ... not the difference from one to the other.
    (that is, the angle that the sine is offset ... i2 looks like a cosine, so make sure your units are correct)
    They both have the same T, and hence the same ω and same ν (or f) .
    the initial time offset does not relate to their repeat time periods.
     
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