PHYSICS 244
                         EXPERIMENT #3
 

Q.1.     Derive the expression mλ = d sin θ 
for light passing through two slits separated by a distance d using
Fig. 1.  Assume that d << L, the distance from the diffraction grating
to the point of measurement.  As in the Bragg scattering formula, you
should calculate the path difference for light passing through the two
slits and then impose the condition for when the light will interfere
constructively.  Note, however, that this formula is not the same as
for Bragg scattering.  Explain the difference.
 

Q.2.     Using the textbook to help you, derive the expression for R
using the Bohr model.  Explain briefly how the quantum mechanical or
"wave" nature of the orbital motion affects the energy of the nth
electronic state in hydrogen and creates the discrete energies of
transition observed in the emission spectrum of hydrogen.  

 
Q.3.     Why can't we see the transitions to the n = 1 ground state?  

Q.4.     What is the mechanism in the hydrogen lamp which causes the
hydrogen molecules to dissociate into atoms and the atomic electrons
to be in higher energy orbital states?