Physical Science multiple choice test….

I have attached the pictures to certain questions at the bottom…. labeled question 3….

1.  Use the equation:

frequency=wavespeed/wavelength

and the wavelength you found in #3 to calculate the frequency of this photon (remember the speed of light is 3E8 m/s):

• 7.6E14 Hz
• 6.0E14 Hz
• 4.6E14 Hz

2. Use the energy equation from this week’s notes, your answer from #5, and Plank’s constant (6.63E-34) to find the approximate energy of this photon:

• 4.8E-19 Joules
• 3.0E-19 Joules
• 3.0E-17 Joules
• 1.21 Gigawatt

3. 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 #3.

Which is the best description of why this occurs?

4. 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.

(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 produces 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: (c=E/p)

where again p is the phonon momentum, E is the photon energy and c is the speed of light.  When you divide the photon energy found in #6 by the photon momentum found in #4, do you get the speed of light?

(If not, check your work for questions #4 through #6).

5. All visible light (light that our eyes can detect) has wavelength between 400-700 nanometers. Wavelengths just smaller than 400 nm are Ultraviolet light. Wavelengths just larger than 700 nanometers are infrared light. What type of light is the Balmer series light that we have consider so far?

• Visible
• Ultraviolet
• Infrared

6. The solar panels used by Mark function because of the photoelectric effect. Light shines on the cells causing electrons to be ejected from the metal, which produces an electric current. At night on Mars, no light will fall on the solar cells and no electric current will be generated. According to your notes, what type of light is typically needed to cause the photoelectric effect?

• Visible
• Ultraviolet
• Infrared

7. If we were to illuminate them only with light from the Balmer transition considered above, would the solar panels produce a current?

8. Starting with only the Balmer series light (visible light), how could we ensure that the solar panels generate a current that Mark can use for his power station? (It may help to look at the electromagnetic spectrum from week 3):

• By gradually increasing the brightness (amount) of light that we shine on it.
• By gradually increasing the frequency of the light we shine on it.
• By gradually increasing the wavelength of the light that we shine on it.

9. 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?

• 0.1c (1/10 the speed of light)
• c (the speed of light)
• 1.1c (c+0.1c)

10. Note: The following questions are unrelated to the Balmer series or The Martian.  Please refer to your course notes.

A Sun-sized star will spend most of its lifetime as a:

• White Dwarf
• Red Giant
• Protostar
• Main-Sequence Star

11. Our Sun will eventually:

• explode in a supernova.
• become a white dwarf star.
• become a black hole.

12. A main sequence star does not expand or contract due to the balance between the internal heat pushing outward and the weight of the material pressing inward due to gravity.  This state of maintaining a constant size is known as:

• hydrostatic equilibrium
• thermal equilibrium
• dynamic equilibrium

13. Neutron stars are:

• 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.
• Incredibly big and massive star remnants which expelled all its neutrons in a supernova explosion.

14. Black holes are:

• 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 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.

15. Which of the following states that all matter tends to “warp” space in its vicinity and that objects react to this warping by changing their paths?

• Newton’s Universal Law of Gravitation
• Einstein’s General Relativity
• Einstein’s Special Relativity
• Newton’s First Law of Motion

16.  Wave-particle duality tells us that wave and particle models apply to all objects whatever the size, so why don’t we observe wave properties in macroscopic objects?

• 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).