Download QUIZ 1 - AY5-S13 . . . . . . . . . . . . . . . . . YOUR NAME

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QUIZ 1 - AY5-S13 . . . . . . . . . . . . . . . . . YOUR NAME:
Possibly useful formulae:
λmax (cm) =
0.29
T(K) ;
λ × f = c (wavelength x frequency = speed); Energy radiated per unit area = σ × T(K)4
Speed of light = c = 300,000 km/sec
1. How long does it take light to travel from the Moon to the Earth, a distance of 384,000 km? By
the way, did you remember to write your name on the quiz?
Time = distance/speed=(384,000km/300,000km/sec)=1.28 seconds
2. When does the new moon rise (the phase when you cannot see any of the illuminated half of the
moon)? Draw a picture of the relative positions of the Moon, Sun and Earth that demonstrate your answer.
Dawn. EARTH—-Moon—-SUN
3. Rank the following in order of increasing wavelength (1 - shortest; 4 - longest):
1 X-rays
4 FM radio (800 MegaHertz)
2 Blue light
3 Infrared
4. A source emits infrared radiation at a wavelength of 1060×10−9 m. What is the frequency of this
radiation?
f=c/λ = (3 × 105 km/sec)/(1060 × 10−9 m)× (1000m/1km)
5. Suppose you have a hot gas of hydrogen and a hot gas of helium, each at the same temperature.
Label the following statements True (T) or False (F).
F The two gases would have identical spectra
F Both gases would show identical emission-line spectra
T The two gases would show different emission-line spectra
F Both would show continuous spectra, with the helium-gas spectrum peaking
at a shorter wavelength
6. What color would a yellow banana slug appear if illuminated with white light? Yellow
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7. Suppose you lived on the Moon where there is essentially no atmosphere. Label the following
statements as (T)rue or (F)alse:
F The Sun would appear redder (compared to as seen from the Earth) during the day.
T The color of the sky (looking away from the Sun during the day) would be black.
F At sunset, the Sun would appear redder than it does at noon.
F The “green flash” would be a “red flash”
8. For a 2900K object, at what wavelength is the peak of the Planck radiation curve?
λmax = 0.29/2900 (units of cm)
9. Based on the schematic diagram below of the allowed energy levels in an atom:
B, C Which transition(s) correspond(s) to the absorption of a photon?
A Which transition corresponds to the lowest energy photon emitted?
D Which transition corresponds to the shortest wavelength energy photon emitted?
A Which transition corresponds to the lowest frequency photon emitted?
A
D
B
C
10. Star A has twice the trigonometric parallax angle and twice the luminosity of Star B. (Assume no
dust toward either star)
a) What are the relative distances of the two stars?
Star A has a larger parallax angle and is therefore closer than Star B. A is 1/2 the distance of B.
b) what are the relative brightnesses of the two stars?
Based on the relative distances, Star A would be 4x brighter than Star B (inverse square law). Based on the
relative luminosities, Star A would be twice as bright. In combination, Star A would be 4 x 2 = 8 times brighter
than Star B