4.3 Knowledge Check
30
Test in WEEK 4
APR
STATUS
1
Knowledge Check: Part A
6
Higher-energy
orbit
ww-Photon
410 nm
434 nm
Lower-energy
orbit
www
486 nm
-WWW
656 nm
23
(a) Electronic emission transition
(b) Balmer series transitions
http://catalog.flatworldknowledge.com/bookhub/4309?e=averill_1.0-ch06_s03
As mentioned in this week's notes on page 4, the electrons of an atom can occupy different energy
shells within the atom (similar to how the planets all occupy different orbits around the Sun).
Electrons prefer to be in the lowest energy shell possible (the ground state); however, they can gain
energy and jump to a higher shell by absorbing light or being exited by an electric current. In
accordance with conservation of energy, if an electron drops from a higher energy level to a lower one,
this must emit a photon (particle of light) with energy equal to the energy difference of the shells.
A Balmer series transition is any transition of an electron from some higher energy shell down to the
second lowest energy shell (n=2) in hydrogen.
Use the momentum equation for light found in this weeks notes and the wavelengths shown in image
(b) above to calculate the momentum of a photon emitted during the Balmer transition from the n=3
shell in hydrogen (remember nm is short for a nanometer, for example 656 nm = 656 x 10-9 meters):
5 Points
O 1.0 x 10^(-27) kg. m/s
O 1.8 x 10^(-27) kg. m/s
2.0 x 10^-27) kg. m/s
O 3.0 x 10^(-27) kg.m/s
N
Use the equation from week 3:
frequency
wavespeed
wavelength
and the image above to calculate the frequency of a photon emitted during this Balmer transition.
Remember the speed of light is 3 x 108 m/s.
5 Points
O 7.6 10^14 Hz
O 6.0 x 10^14 Hz
4.6 x 10^14 Hz
3
Use your answer from #2, and Plank's constant (6.63 x 10-34 J • s) to find the approximate energy of
this photon:
5 Points
4.8 x 10^-19) Joules
3.0 x 10^-19) Joules
3.0 x 10^(-17) Joules
O 1.21 Gigawatts
4
V B
G
Narrow slit
Thin ribbon
of light
Screen of
photographic
plate
Lens
Prism
Tube containing
excited H, gas
(b)
(a)
http://catalog.flatworldknowledge.com/bookhub/4309?e=averill_1.0-ch06_s03
A glass tube is filled with hydrogen gas. An electric current is passed through the tube, and the tube
begins to glow a pinkish/purple color (this is how fluorescent bulbs and neon signs produce light). If
you were to pass this pink light through a prism to separate the individual light frequencies, you would
see that this pink light is composed of four distinct colors: violet, green, blue, and red. Notice the
similarity between image (b) above and image (b) from question 1.
Which is the best description of why this occurs?
5 Points
The electrons within the hydrogen atoms gain energy from the current causing them to jump to higher energy orbitals. When they fall
back to a lower energy orbital they release a single photon. These photons have discrete energies equal in to the difference in energy
of the two orbitals.
Atoms contain continuous energy orbitals, meaning that the light the hydrogen atoms produce can be of any energy. Depending on the
type of prism used, when the light reaches it, the prism will only allow specific light energies (frequencies) to pass through.
As Max Planck explained, the emission of light from any atom has energies of some constant times the frequency of the light: E = hf.
Thus, the light spectrum from any source contains all colors (frequencies) because the Planck constant, h, is so small.
O Because Chuck Norris said so.
5
The lights used by Mark Watley (played by Matt Damon) during the film The Martian seem to be Metal
Halide lamps. Metal Halide lamps are filled with vaporized mercury and metal-halogen compounds.
When an electric current is passed through the lamp, the tube begins to glow a bright white/blue
color.If you were to pass this light through a prism to separate the individual light frequencies, you
would see a rainbow just as you would if using natural sunlight because of the complexity of the metal
halide gas and the vast amount of possible electron transitions possible.
(The study of light in this way is known as spectroscopy and allows astronomers to know exactly what atoms
compose distant stars, simply by looking at the light they emit. The spectral lines an atom produce uniquely
identifies that atom just like a fingerprint uniquely identifies a person.)
The momentum equation and energy equation that we have used above can be combined to give the
following equation:
E
C =-
P
where again p is the phonon momentum, E is the photon energy and c is the speed of light. When you
divide the phonon energy found in #3 by the phonon momentum found in #1, do you get the speed of
light?
(If not, check your work for questions #1 through #3).
5 Points
Yes
ОО
O No
6
The solar panels used by Mark function because of the photoelectric effect. At night on Mars, no light
will fall on the solar cells and no electric current will be generated.If we were to illuminate them only
with light from the Balmer transition considered above, would the solar panels produce a current?
Hint: Note where this light falls on the electromagnetic spectrum and the type of light mentioned in
the notes that is typically associated with the photoelectric effect.
5 Points
Yes
O No
7
Starting with only the Balmer series light, how could we ensure that the solar panels generate a
current that Mark can use for his power station? (refer to the electromagnetic spectrum presented in
week 3 if needed):
5 Points
By gradually increasing the brightness (amount) of the Balmer series light that we shine on it.
By gradually increasing the frequency of the light that we shine on it.
O By gradually increasing the wavelength of the light that we shine on.
8
Imagine you are riding on a yacht in the ocean and traveling at 20 mph. You then hit a golf ball at 100
mph from the deck of the yacht. You see the ball move away from you at 100mph, while a person
standing on a near by beach would observe your golf ball traveling at 120 mph (20 mph + 100 mph).
Now imagine you are aboard the Hermes spacecraft traveling at 0.1c (1/10 the speed of light) past
Mars and shine a laser from the front of the ship. You would see the light traveling at c(the speed of
light) away from your ship. According to Einstein's special relativity, how fast will a person on Mars
observe the light to be traveling?
5 Points
O 0.1 c (1/10 the speed of light)
C(the speed of light)
1.1C (C+0.10)
9
Knowledge Check: Part B
Find a picture from a media source (movies, TV, comics, video games, etc.) that takes place in outer
space. Place the picture in the following diagram template and cite the image using APA format:
Keynote: Week 4DiagramTemplate.key
PowerPoint: Week4DiagramTemplate.pptx
If you need help learning how to manipulate the template in Keynote checkout this Lynda.com video series.
For a different version of Keynote, power point or other software, just search in lynda.com for other great
courses.
If you are unable to open either of the diagram templates for any reason, please use the image below as a
guideline in creating your own diagram in another presentation-based software program.
WEEK 4 DIAGRAM TEMPLATE
Object that warps
spacetime the most
Type the name of the object
that warps spacetime the
most here.
Place picture here.
Object that warps
spacetime the least
Type the name of the object
that warps spacetime the
least here.
O
Path of object due to
gravitational forces
Citation:
Area where dark
matter may be
present
Insert citation for your image here.
Answer the following questions based on the picture chosen and what you have learned this week.
Quantum mechanics is:
4 Points
the science of the origin, development, and fate of the universe.
a branch of science that deals with celestial objects.
O a mathematical formalism concerning physical phenomena in atomic scales 10^-9 meters or less.
10
What is the wave-particle duality?
4 Points
Wave model applied to radiation (light).
Wave and particle models applied to all objects whatever the size.
O Particle model applied to macroscopic objects.
11
Why don't we observe wave properties in macroscopic objects?
4 Points
Because their particle properties forbid us from observing their wave properties.
Because their wavelength is extremely long (undetectable).
Because their wavelength is extremely short (undetectable).
12
What is the state of the system?
4 Points
O It is defined by the minimum amount of information which is sufficient to determine the conditions of the system.
It is defined by any quantity of information used to describe the conditions of the system.
It is defined by the maximum amount of information used to determine the conditions of the system.
13
In Classical Physics, the state of the system at a given time is completely determine by:
4 Points
The mass and velocity.
O Velocity and momentum.
O Coordinates and the momentum.
14
In quantum mechanics, the state of the system is specified by:
4 Points
The state or wave function.
O Coordinates and momentum.
Particle's mass and velocity.
15
What is a main sequence star?
4 Points
A star more massive than the Sun which energy comes from nuclear fusion reactions.
O A star with hydrostatic equilibrium, thermal equilibrium and which main source of energy comes from the nuclear fusion of hydrogen
in the core.
A star with hydrostatic equilibrium, thermal equilibrium and which main source of energy come from the nuclear fission of hydrogen in
the core.
16
What is a white dwarf?
4 Points
O A small star that radiates white light.
O A star remnant with a core that is extremely hot, dense and small and which eventually stops radiating light as it cools.
A star remnant with a low density core, with high (white) luminesce.
17
Neutron stars are:
4 Points
O Low density star remnants with many neutrons, which mass is less than the mass of the Sun.
Incredibly small remnants of super massive stars where the gravitational collapse is stop by neutron degeneracy.
O Incredibly big and massive star remnants which expelled all its neutrons in a supernova explosion.
18
Black holes are:
4 Points
Star remnants from super massive stars which gravitational collapse can not be halt by electron or neutron degeneracy and gravity is
so strong in their vicinity that nothing, not even light can escape.
Regions of the universe with space empty of matter or radiation that becomes so dark that forbids us from investigating it.
Regions of space where matters is not sufficiently hot to radiate in the visible spectrum.
19
1. Take a screen shot of your completed Week 4 Diagram using the Command+Shift+4 keyboard
shortcut. Please paste it in the comments section for this question.
If you need help learning how to manipulate the template in Keynote checkout this video:
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