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Physics 101A Modern Physics Winter 1998
Final Exam
March 20, 1998
Some physical constants:
• Speed of light: c=3.00×108 m/s.
• Stefan-Boltzmann constant: σ=5.67×10-8 W/(m2K4).
• Planck’s constant: h=6.63×10-34 J s, hc=1970 eV Å.
• Electron mass: kg 1011.9 31−
⋅=
e
m, eV 511000
2=cmc.
• Electron charge: C 1060.1 19−
⋅−=− e.
This exam includes 17 problems on 3 sheets and 6 pages. Please work problems 1
through 12 on this paper and 13 through 17 on separate paper.
1) (2 pnts) The ground state (n=1) of the hydrogen atom has one unit of orbital angular
momentum (in units of h.)
a) True
b) False
2) (2 pnts) Light of frequency ν shines on a metal surface and photoelectrons are
emitted. Each electron emitted from the surface has a kinetic energy given by
φ
ν
−= hE
where
φ
is a constant for a given metal called the “work function.”
a) True
b) False
3) (2 pnts) In a Compton scattering experiment light of wavelength λ incident on a solid
target emerges with a longer wavelength λ′. The observed increase in wavelength is
due to
a) scattering from individual atomic nuclei.
b) coherent scattering from planes of atoms.
c) scattering from individual quasi-free electrons.
d) inelestic scattering from an atom in which the atom is excited into one of its
higher bound states.
4) (2 pnts) An electron and a photon with the same energy have the same de Broglie
wavelength.
a) True
b) False
5) (2 pnts) Eigenfunctions of the Schrödinger equation are always either even or odd
under space inversion,
x
x
vv −→ .
a) True
b) False
Name:
Problem Possible Score
1–5 10
68
7–11 11
12 10
13–15 31
16,17 30
Total
