Transcript PHY 231 Lecture 29 (Fall 2006)

Physics 213
General Physics
Final Review 1
A hydrogen atom in the ground state absorbs a 12.75-eV
photon. To what level is the electron promoted? (The
ionization energy of hydrogen is 13.6-eV).
1.
2.
3.
4.
5.
n=2
n=3
n=4
n=5
n=6
1
The quantum mechanical model of the hydrogen atom requires
that if the orbital quantum number = 5 for a specific principal
quantum number state, how many possible substates exist for
that specific orbital?
1.
2.
3.
4.
5.
5
8
10
11
22
2
Which of the following transitions in hydrogen from an initial
state (ni) to a final state (nf) results in the most energy emitted?
(a) ni = 80, nf = 2
(b) ni = 3, nf = 95
(c) ni = 2, nf = 1
(d) ni = 1, nf = 3
(e) ni = 95, nf = 3
3
A flame emits light as an ideal blackbody. When is the flame
hotter; when it glows red or blue?
4
If the flame is at a temperature such that it is mostly emitting
red visible light, we can assume all of the visible photons have
a wavelength of approximately 630 nm. If the power of visible
light emitted by the flame is 2 watts, approximately how many
visible photons per second are emitted by the flame? (h = 6.63
x 10-34 Js = 4.14 x 10-15 eVs, c=3 x 108 m/s)
5
Surface #1 has work function j1, and when bombarded with
photons of wavelength l1 emits photoelectrons with maximum
energy KE1. Surface #2 has work function j2, and when
bombarded by photons of wavelength l2 emits photoelectrons
with maximum energy KE2. If j1 > j2, then which of the
following must be true?
1. KE1 > KE2
2. l1 > l2
3. lC for surface #1 is greater
than lC for surface #2.
4. lC for surface #2 is greater
than lC for surface #1.
5. None of the above.
6
As the temperature of a radiation emitting blackbody becomes
higher, what happens to the peak wavelength of the radiation?
1.
2.
3.
4.
5.
Increases.
Decreases.
Remains constant.
It is directly proportional to
temperature.
None of the above.
7
A mass is bouncing on the end of a spring with a period T
when measured by a ground observer. What would the period
of oscillation be (as measured by the same observer) if the
mass and spring were moving past the ground observer at a
speed of 0.80 c?
1. 0.44 T
2. 0.60 T
3. 1.0 T
4. 1.7 T
5. 2.7 T
8
How fast would a rocket have to move past a ground observer
if the latter were to observe a 4.0% length shrinkage in the
rocket length? (c = 3.00  108 m/s)
1.
2.
3.
4.
5.
0.12  108 m/s
0.28  108 m/s
0.85  108 m/s
1.2  108 m/s
3.1  108 m/s
9
A given individual is able to see objects clearly only when
they are beyond 100 cm. If this person would like to be
able to read text held as close as 25.0 cm from their eye,
what focal length eye glasses should be used?
1.
2.
3.
4.
5.
100 cm
25.0 cm
75.0 cm
100 cm
33.3 cm
10