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Homework Help: Please help! Problems on particle-in-a-box models

  1. Sep 11, 2012 #1
    The normalized wave function for a particle in a 1D box in which the potential energy is zero
    between x= 0 and x= L and infinite anywhere else is

    normalized wave function = sqrt(2/L)*sin(npix/L)

    What is the probability that the particle will be found between x= L/4 and x= L/2 if the particle is in the state characterized by the quantum number n= 1?

    Hint given:

    indefinite integral of sin^2(ax)dx = .5x - .25asin(2ax)
  2. jcsd
  3. Sep 11, 2012 #2
    What you probably don't know (but should know) is that
    P(particle between a and b)=∫_a^b |ψ(x)|^2 dx
    where ψ is the wavefunction of the particle.
  4. Sep 11, 2012 #3
    I am confused as to what I use the second formula for... How do I find the probability of the particle being located in the region bounded by x=l/4 and x=l/2? How do i get an actual value for this since L is being used, and not a real number?
  5. Sep 11, 2012 #4
    How about you do the calculation and see what you end up with? There is a possibility that L cancels out...
    Btw.: Which one is the second formula for you?
  6. Sep 11, 2012 #5
    indefinite integral of sin^2(ax)dx = .5x - .25asin(2ax)

    that is the second formula. and I tried working it out but I couldn't get L to cancel out.. i just got an ugly answer...
  7. Sep 11, 2012 #6
    Please write down your entire calculation then I can help you with it.
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