This week's questions test whether you understand the hydrogen energy level diagram and also the new reading from the Walker handout (read up through the end) and Universe, section 19(5) and also box 7-2

    1.  At the end of class today we realized that small n values correspond both to small orbit radius and small energy.  If we put in numbers for some small values of n (1 through 4) and calculate the energies according to the equation 31-9, we would find that the allowed energies are those shown in the Walker handout on page 1020.

Now look at figure 5-23 in Universe, which shows the same energy level diagram for hydrogen, but with different values for the energies of the lowest four levels!

How can this be?  How can the energy levels have different values in different books?

To explain why this is OK, how are Walker numbers related to the Universe numbers (for the lowest 4 energies)?
What did Universe apparently do differently in deriving their energy values than Walker did?  And why is this OK, physics-wise?  Whose diagram is correct as to scale?

   2.  Suppose we are interested in finding the transitions that electrons can make that will produce visible light.

a) first, must electrons increase or decrease their orbit size to emit light?

b) in the photon energy-wavelength relationship (Universe page 104), the constant hc has a value of 1240 ev-nm (electron volt-nanometers).  (Surely you checked this).  Since you know the range of visible light in nm, calculate the energy range of visible-light photons in electron volts.

c) Using trial and error on the 4 energy level values in the hydrogen energy-level diagram in Universe (page 115), 
which transitions (from level what to level what) would produce/emit a visible-light photon?

for all those that you find, give

(1) the initial and final transition levels of the electron
(2) the energy of the visible photon produced (in ev)
(3) the wavelength of the photon produced (in nm)

   3. a) Can the neutral hydrogen atom emit spectral lines at x-ray wavelengths?  If so, convince me how (perhaps by presenting a sample transition).  If not, be convincing as to why not.

b) Can the neutral hydrogen atom emit spectral lines at radio wavelengths?  If so, convince me how (perhaps by presenting a sample transition).  If not, be convincing as to why not.