Physlets run in a Java-enabled browser, except Chrome, on the latest Windows & Mac operating systems. If Physlets do not run, click here for help updating Java & setting Java security.
Problem 10.1: Compare classical and quantum infinite square well probability distributions
Please wait for the animation to completely load.
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?