Densen
PHY HW4
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Rebecca 121, Fall 2011
Instructor: Dejan Stojkovic
HW4 (Homework)
Current Score : 8 / 10
Due : Friday, October 14 2011 08:09 PM EDT
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1. 1/1 points | Previous Answers
SeedsHorizons12 5.P.01.
The thickness of the plastic in plastic bags is about 0.001 mm. How many wavelengths of red
light is this? (Assume a wavelength of 650 nm for red light.)
1.54
1.54 wavelengths
2. 1/1 points | Previous Answers
SeedsHorizons12 5.P.02.
What is the wavelength of radio waves transmitted by a radio station with a frequency of 180
million cycles per second?
1.67
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1.67 m
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3. 2/2 points | Previous Answers
SeedsHorizons12 5.P.05.
What is the resolving power of a 38 cm telescope?
.305
0.305 seconds of arc
What do two stars 1.5 seconds of arc apart look like through this telescope?
The total distance from one outside edge of the star to the outside edge of the other star will
be .305 seconds of arc apart. The number is relatively small so the detail will not be that
good. they will appear closer together than 1.5 seconds of arc they might even appear to be
one star because of the quality of the telescope.
Key: The two points of light are well separated from each other.
4. 3/3 points | Previous Answers
SeedsHorizons12 5.P.07.
How does the resolving power of a 5 m telescope with compare that of the Hubble Space
Telescope?
resolving power of 5 m telescope
.0232
0.0232 seconds of arc
resolving power of HST
.048
0.0483 seconds of arc
Why does the HST outperform the 5 m telescope?
Because its resolving power is larger. It makes the view more detailed, and shows more of the
stars.
Key: Earth's atmosphere affects the seeing for the 5 meter telescope and limits resolving
power to about 0.5 seconds of arc. The HST is not affected by seeing distortion due to the
atmosphere.
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5. 0/1 points | Previous Answers
SeedsHorizons12 5.GP.01.
Based on what you learned about light, select all of the correct statements from the following
list.
A photon is a particle of light.
All electromagnetic waves travel at the speed of light.
Different types of electromagnetic radiation are fundamentally different types of
waves.
Light can act both as a wave and a particle.
The only type of electromagnetic radiation that is actually considered light is visible
light.
High frequency photons carry more energy than long wavelength photons.
X-rays and gamma rays are long wavelength photons.
3 of 4
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6. 0/1 points | Previous Answers
SeedsHorizons12 5.GP.02.
Based on what you learned about telescopes, select all of the correct statements from the
following list.
Chromatic aberration limits the useful size of any type of telescope.
Recently built modern telescopes are reflectors.
The largest telescopes are refractors.
The diameter of a telescope controls its magnification.
Telescopes linked together as an interferometer have an effective size equal to the
size of the telescopes added together.
4 of 4
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