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# Problem 10.1: Compare classical and quantum infinite square well probability distributions

**Position Graph** | **Velocity Graph** | **Position Graph** | **Momentum Graph**

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The normalized classical probability distributions and quantum-mechanical probability densities for the infinite square well are shown in position and momentum space. Restart.

- Click on "Position Graph" below the right-hand graph. The graph shows the probability that a particle is in the ground state at some position
*x*. You may vary*n*to see higher energy states. Under the left-hand graph, a ball is bouncing back and forth between the two walls. What does the classical probability distribution as a function of*x*look like? Briefly discuss your reasoning.__After you answer__, click "Position Graph" below the left-hand graph and check your answer. Explain why your answer agreed with, or disagreed with, the given answer. - Under what conditions
*could*the right-hand graph look like the left-hand graph? In other words, what is the correspondence between the classical probability distribution and quantum position probability of a particle in a 1-d box? Check your answer using the "Position Graph" buttons. - Click on "Momentum Graph" on the right-hand graph. Displayed is a graph of the probability density in momentum space as a function of
*p*. The box <*p*> gives the expectation value of the momentum of the particle. Now click on "Velocity Graph" on the left-hand graph. What is the difference you see? Why does this difference exist?

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