Using your results above, n, the number of de
Broglie wavelengths 
which fit in the circumference an
orbit of radius r. that
If we assume that to avoid destructive interference that n must be
a natural number 
, then this result tells you the
allowed radii for the orbits of the mass m. Under the same
assumption, determine the allowed momenta p and the allowed energies
E for the particle.
Hint: You should find that the allowed energies are
where 
.