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Astronomy
Chapter 4
Name: ________________________________
Worksheet 1
Block: ________________________________
Match the definition to the correct word or term
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1. Absorption
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2. Absorption-line spectrum
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3. Atmospheric window
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4. Blackbody
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5. Conservation of energy
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6. Continuous spectrum
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7. Doppler shift
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8. Electromagnetic radiation
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9. Electromagnetic spectrum
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10. Electromagnetic wave
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11. Elements
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12. Emission
13. Emission-line spectrum
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14. Energy levels
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15. Excited
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16. Frequency
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17. Infrared
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18. Light
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19. Nanometer
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20. Orbital
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21. Photons
A. An object that is an ideal radiator when hot and a perfect
absorber when cool
B. A particle of visible light or other electromagnetic radiation
C. A fundamental substance that cannot be broken down into
a simpler chemical substance
D. The study and analysis of spectra
E. A wave consisting of alternating electric and magnetic
energy
F. The theory that electromagnetic radiation may be treated as
either a particle or an electromagnetic wave
G. Any of the numerous levels that an electron can occupy in
an atom
H. A principle of physics stating that energy is never created or
destroyed although it may change its form
I. A wavelength of electromagnetic radiation longer than
visible light but shorter than radio waves
J. The part of the electromagnetic spectrum that we can see
with our eyes
K. The change in the observed wavelength of radiation
caused by the motion of the emitting body or the observer
L. Electromagnetic energy
M. A relationship between a body’s temperature and the
wavelength at which it emits radiation most intensely
N. The process in which light or other electromagnetic
radiation gives up its energy to an atom or molecule
O. A unit of length equal to one-billionth of a meter
P. The production of electromagnetic radiation by an atom or
other object
Q. The assemblage of all wavelengths of electromagnetic
radiation
R. The condition in which the electrons of an atom are not in
their lowest energy level
S. A spectrum in which certain wavelengths are darker than
adjacent wavelengths
T. The property of a system that allows it to have only discrete
values
U. The number of times per second that a wave vibrates
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22. Quantized
V. A wavelength band in which our atmosphere absorbs little
radiation
W. Visible light exhibiting no color of its own but composed of a
mix of all colors
X. A spectrum consisting of bright lines at certain wavelengths
separated by dark regions in which there is no light
Y. The distance between wave crests
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23. Spectroscopy
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24. Ultraviolet
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25. Visible spectrum
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26. Wavelength
Z. The portion of the electromagnetic spectrum with
wavelengths shorter than that of visible light but longer than
that of X-rays
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27. Wave-particle duality
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28. White light
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29. Wien’s law
AA. A spectrum with neither dark absorption nor bright emission
lines
BB. A spectrum showing dark lines at some narrow color
regions
CC. A general term for any kind of electromagnetic wave
Circle the letter that corresponds to the correct answer
30. What kind of light travels fastest?
a. Ultraviolet
b. Visible
c. Gamma ray
d. Radio waves
e. They all travel at the same speed
31. Which type of electromagnetic radiation has the longest wavelength?
a. Ultraviolet
b. Visible
c. X-ray
d. Infrared
e. Radio
32. Which kind of photon has the highest energy?
a. Ultraviolet
b. Visible
c. X-ray
d. Infrared
e. Radio
33. Suppose we detect red photons at 656 nanometers emitted by electrons dropping from the n=3 to
n=2 orbital in hydrogen. The hydrogen is in an interstellar cloud at 5000K. If the cloud were heated to
10,000 K, what would be the wavelength of the photons emitted by the transition?
a. 328
b. 656
c. 1312
d. 658
e. 654
34. An astronomer finds that the spectrum of a mysterious object shows bright emission lines. What can
she conclude about the source?
a. It contains cold gas
b. It is an incandescent solid body
c. It is rotating very fast
d. It contains hot, relatively tenuous gas
e. It is moving toward Earth at a high speed
35. A star’s radiation is brightest at a wavelength of 400 nanometers. Its temperature is about
a. 4000 K
b. 12,000 K
c. 1500 K
d. 750 K
e. 7500 K
36. If an object’s spectral lines are shifted to longer wavelengths, the object is
a. Moving away from us
b. Moving toward us
c. Very hot
d. Very cold
e. Emitting X-rays
Answer the following questions
37. Why is light called electromagnetic radiation?
38. Name the regions of the electromagnetic spectrum from short to long wavelengths
39. Which gases in the atmosphere absorb infrared radiation? Which gases absorb ultraviolet?
40. Why don’t atoms emit a continuous spectrum?
41. How can you tell what sort of gas is emitting light?