How do you solve for multiple constants given the wave functions at the boundary?

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Homework Help Overview

The discussion revolves around solving for multiple constants in wave functions at a boundary, specifically focusing on the conditions at x = a where the wave functions ψ1 and ψ2 are evaluated.

Discussion Character

  • Conceptual clarification, Assumption checking

Approaches and Questions Raised

  • Participants discuss equating the wave functions at the boundary and the implications of continuity for the first derivative. There is a focus on the correct interpretation of boundary conditions and the continuity requirements.

Discussion Status

The conversation is exploring the necessary conditions for the wave functions at the boundary, with some participants providing clarifications on the correct application of continuity for both the wave functions and their derivatives. There is an indication of progress as one participant expresses gratitude for the assistance received.

Contextual Notes

There appears to be some confusion regarding the application of boundary conditions and the continuity of derivatives, which may affect the understanding of the problem setup.

Danielk010
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Homework Statement
In the region 0 ≤ x ≤ a, a particle is described by
the wave function ψ1(x) = ##−b(x^2 − a^2 )##. In the region
a ≤ x ≤ w, its wave function is ψ2(x) = ##(x − d)^2 − c##. For
x ≥ w, ψ3(x) = 0. (a) By applying the continuity conditions
at x = a, find c and d in terms of a and b. (b) Find w in terms of
a and b.
Relevant Equations
ψ1(x) = ##−b(x^2 − a^2 )##. 0 ≤ x ≤ a
ψ2(x) = ##(x − d)^2 − c##. a ≤ x ≤ w
ψ3(x) = 0 x ≥ w
From my understanding, you can equate ψ1(x) and ψ2(x) at the boundary of x = a, so I plugged in the values of a into x for both equations and I got ψ1(x) = 0 and ψ2(x) = ## (a-d)^2-c ##. I am a bit stuck on where to go from here.
 
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Danielk010 said:
and I got ψ1(x) = 0 and ψ2(x) = ## (a-d)^2-c ##. I am a bit stuck on where to go from here.
No. You got ψ1(a) = 0 and ψ2(a) = ## (a-d)^2-c ##. Equating ψ1 and ψ2 at x=a means you have ψ1(a) = ψ2(a)

Then: what about continuity of the first derivative ?

##\ ##
 
BvU said:
No. You got ψ1(a) = 0 and ψ2(a) = ## (a-d)^2-c ##. Equating ψ1 and ψ2 at x=a means you have ψ1(a) = ψ2(a)

Then: what about continuity of the first derivative ?

##\ ##
The continuity for the first derivative of which wave function?
 
BvU said:
No. You got ψ1(a) = 0 and ψ2(a) = ## (a-d)^2-c ##. Equating ψ1 and ψ2 at x=a means you have ψ1(a) = ψ2(a)

Then: what about continuity of the first derivative ?

##\ ##
I got it. Thank you so much for the help
 
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