This applet illustrates a hydrogen atom according to particle or wave model. You can choose a principal quantum number n(with slider). The right part of the graphics represents the energy levels of the atom. You can read off the orbital radius r and the total energy E.
This simulation is similar to the one at http://www.walter-fendt.de/ph11e/bohrh.htm
Default setting is the particle mode. you can switch to wave mode.
It will switch to wave mode when you click and drag within simulation region.
If you try to vary the orbit's radius with pressed mouse button, this will generally lead to a non-stationary state. You can realize that by using the option "Wave model".