With the aid of this applet you can understand about all there is to know about the Bohr Model of the hydrogen atom.
With the buttons on the right, you can select the series of transitions you would like to study. The numbers next to the buttons mark the orbit that the electron jumps into during emission of a photon.
You can then click on an electron orbit, and if the transititon is possible, then you will see an arrow corresponding to this transition.
In the lower left corner is an energy diagram, in which you can also see the transition, and the energy difference is calculated.
On the top of the applet, we show all hydrogen spectral lines between 0 and 2000 nm. (Remember, the visible range is between 400 and 650 nm!). If you have a transition, and its wavelength falls within the range 0 to 2000, its spectral line is highlighted. If the transition falls into the visible region, then we also show the color of the line. [However, this happens only for four lines in the Balmer series.]