# Which number should I suppose to $a$ (width of well) and $m$ (mass of particle) in potential well problem? [closed]

I tried to plot a complete of state functions of potential well problem but graph was so weird. I thought a cause was variables a and m were not consistent with scale of quantum world. For m i might be can guess but for a i have no idea.

The wave function is:

Y(x) = Ax(x-a)      ,where a is width of well


How should i set a (width of well) and m (mass of particle)?

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## closed as off-topic by tpg2114, Brandon Enright, Qmechanic♦Dec 3 '13 at 0:59

This question appears to be off-topic. The users who voted to close gave this specific reason:

• "Homework-like questions should ask about a specific physics concept and show some effort to work through the problem. We want our questions to be useful to the broader community, and to future users. See our meta site for more guidance on how to edit your question to make it better" – tpg2114, Qmechanic
If this question can be reworded to fit the rules in the help center, please edit the question.

Hi terces907, could you please edit your question so that one can understand what you are exactly asking. 'Graph was so weird' does not explain what might be wrong. Are you trying to plot a 'particle in a box'? If so the corresponding wikipedia article explains in detail how this is done. Your trial wave function is just a parabola. –  Alexander Nov 10 '13 at 13:02

I would suggest playing around with values of $a$ that are multiples of the wavelength of your particle. i.e. $\lambda = h/p$, try $a=\lambda$, $2\lambda$, $2\lambda/3$... etc
You can always rescale your coordinates in terms of a new variable $x' = \frac{x}{a}$ so that when $x=a$, $x'=1$, and then just plot from $x=0$ to $x=1$. This is good practice for when you don't have explicit values for your parameters.