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Homework Statement
I need Part B of this question
http://physics.wustl.edu/classes/FL2013/217/homework/ps03.pdf
Recall that the free particle Schr¨odinger equation,
i~
∂
∂tψ(x, t) = −
~
2
2m
∂
2
∂x2
ψ(x, t) (1)
has solutions of the “plane wave” form
ψk(x, t) = exp[ikx − iω(k)t] , (2)
where ω(k) = ~k
2/2m.
(a) (10 points)
Consider φ1(x, t) = cos(k0x − ω(k0)t). Show that φ1(x, t) is not a solution of the
Schr¨odinger equation, i.e. when plugged into both sides of the equation, identity
does not hold for all x and t as long as k0 6= 0.
(b) (10 points)
Find a solution φ2(x, t) to the Schr¨odingier equation that also satisfies φ1(x, 0) =
φ2(x, 0). (Hint: Write cos(k0x) as the sum of a right moving and a left moving
plane wave the way we did in class, and use the superposition principle. That
is, if you know the correct time dependence for each term in the sum, see class
notes, then you also know the correct time dependence of their sum.)
Homework Equations
The Attempt at a Solution
I thought the solution may be φ(x, t)=Ae(-k1x-ω1t)+Ae(-k2x-ω2t)
but I don't think it works out
Anyone have any idea how to solve Part B?
Thanks!
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