User question: incorrect wavelength in Bohr model

[oliver-phet]

Dear People at Phet,

First of all thank you very much for these amazing simulations, I use them a lot!

On the hydrogen atom one https://phet.colorado.edu/en/simulation/legacy/hydrogen-atom I do not get the correct wavelengths in Bohr model.

For example, in the 6 to 5 transition, I calculate the wavelength to be 7460 nm. This calculation is consistent with the page: https://en.wikipedia.org/wiki/Hydrogen_spectral_series

However, your app gives it as 780 nm, please see the attached print-screen.

I was wondering if you could please check.

[amyh-phet]

@oliver-phet Did the user include some sort of screen-shot with this report? I can't reproduce the issue they are reporting.

[oliver-phet]

Sorry, here's the screenshot!

[amyh-phet]

I was able to recreate this behavior. Need to check into why a n=6 to n=5 transition results in an emission of a photon at 780 nm rather than at 7460 nm.

[pixelzoom]

Un-deferring, since development on this sim has resumed.

[pixelzoom]

Note to self, for future investigation...

de Broglie, Schrodinger, and Bohr all use the same transition wavelengths. The Java implementation lives in BohrModel.js, and has not been ported to TypeScript yet. The transition wavelengths are computed by this method:

    /**
     * Gets the transition wavelengths for a specified state.
     * @param state
     * @return double[]
     */
    public double[] getTransitionWavelengths( int state ) {

I'm not sure why the photon wavelength would be correct for Bohr, but incorrect for de Broglie. DeBroglieModel extends BohrModel and there nothing in DeBroglieModel.java that overrides the Bohr behavior.

Transition wavelengths used to label the light's wavelength slider are computed by this method:

    /**
     * Gets the set of wavelengths that cause a state transition.
     * When firing white light, the gun prefers to firing these wavelengths
     * so that the probability of seeing a photon absorbed is higher.
     * 
     * @param minWavelength
     * @param maxWavelength
     * @return double[]
     */
    public static double[] getTransitionWavelengths( double minWavelength, double maxWavelength ) {

[pixelzoom]

Note that the Java versions shows the correct wavelength (7460 nm) for n=6 to n=5 transition, see Help > Transitions dialog below.

If there is a bug, it's also not clear whether there's a problem with emissions only (n=6 → n=5) or also with absorption (n=5 → n=6).