Where Is the Average Position of a Particle in a Box?

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The average position of a particle in a one-dimensional box is computed using the wave function derived from quantum mechanics. The expression for the average position <x> includes a term that accounts for the particle's offset from the origin, represented by x_0. When x_0 is set to zero, the average position simplifies to L/2, which aligns with expectations for a particle centered in the box. However, for non-zero x_0, the additional term arises due to the wave function's shift. This highlights the importance of correctly incorporating x_0 into the wave function for accurate calculations.
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(Example 6.15 from Modern Physics 3e- Serway)

Homework Statement


Compute the average position <x> for the particle in a box assuming it is in the ground state

Homework Equations


<br /> |\Psi|^2=(2/L)\sin^2{(\pi x/L)}<br />
<br /> &lt;x&gt; = \int^{x_0+L}_{x_0}x|\Psi|^2dx<br />

The Attempt at a Solution


<br /> &lt;x&gt;=x_0+L/2-\frac{L}{2\pi}\sin{\frac{2\pi x_0}{L}}<br />

I'm pretty sure this is the answer, however, I don't understand why I get that last term, I mean, the average position should be x_0 + L/2 right?

If I take x_0=0 then the answer is what I was hoping for (Indeed this is the original procedure in the book), but in the more general expression with x_0 \neq 0 I get the previous answer.
 
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If you take the well with x_0 at the left side, then your wavefunction should also be shifted with respect to the solution for x_0=0.

You're missing x_0in the expression for the wavefunction.
 
right! Thanks.
 

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