A Plot of the Continuous Spectra of Five Different Stars is Shown in the Figure Lizyadahken

Homework 5

Multiple Choice

Identify the letter of the choice that best completes the statement or answers the question.

1. Absolute zero is

a.	zero degrees Celsius.
b.	the temperature at which atoms have no remaining energy from which we can extract heat.
c.	the temperature at which water freezes.
d.	both a and c
e.	none of the above

2. The neutral hydrogen atom consists of

a.	one proton and one neutron.
b.	one proton.
c.	one proton, one neutron, and one electron.
d.	one proton and one electron.
e.	an isotope and an ion.

3. The process of removing an electron from a stable nucleus is known as

a.	ionization.
b.	Doppler broadening.
c.	collisional broadening.
d.	a red shift.
e.	quantum mechanics.

4. A plot of the continuous spectra of five different stars is shown in the figure below. �Based on these spectra, which of the stars is the hottest?

a.	Star A
b.	Star B
c.	Star C
d.	Star D
e.	Star E

5. A plot of the continuous spectra of five different stars is shown in the figure below. �Based on these spectra, which of the stars has the lowest temperature?

a.	Star A
b.	Star B
c.	Star C
d.	Star D
e.	Star E

6. An atom can be excited

a.	if it emits a photon.
b.	if it collides with another atom or electron.
c.	if it absorbs a photon.
d.	a and b above
e.	b and c above

7. A(n) __________ contains two or more atoms that are bound together by sharing electrons with each other.

a.	nucleus
b.	ion
c.	proton
d.	electron cloud
e.	molecule

8. The __________ of a gas is a measure of the average speed of the particles in the gas.

a.	heat
b.	composition
c.	temperature
d.	blue shift
e.	binding energy

9. In the diagram below, which of the transitions would absorb a photon with the smallest energy.

a.	Transition 1
b.	Transition 2
c.	Transition 3
d.	Transition 4
e.	Transition 5

10. In the diagram below, which of the transitions would absorb a photon with the greatest energy.

a.	Transition 1
b.	Transition 2
c.	Transition 3
d.	Transition 4
e.	Transition 5

11. An atom that is excited

a.	is also ionized.
b.	is an isotope.
c.	has had its electron moved to the lowest energy level.
d.	can emit a photon when the electron moves to a lower energy level.
e.	can emit a photon when the electron moves to a higher energy level.

12. The lowest energy level in an atom is

a.	the absolute zero temperature.
b.	the ground state.
c.	the ionization level.
d.	responsible for Doppler shifts.
e.	the energy level from which the Paschen Series of hydrogen originates.

13. The two most abundant elements in the sun are

a.	nitrogen and oxygen.
b.	hydrogen and helium.
c.	sulfur and iron.
d.	carbon and hydrogen.
e.	carbon and nitrogen.

14. You are standing near a railroad track and a train is moving toward you at 60 mph and blowing its horn. �What will you notice as the train moves past you?

a.	As the train approaches, the horn will sound lower in pitch than when the train is moving away.
b.	As the train approaches, the horn will sound higher in pitch than when the train is moving away.
c.	There will be no change in the pitch of the horn as it moves by.
d.	The horn will get louder as the train moves away from you.
e.	The horn will get quieter as the train moves toward you.

15. Which of the following can be determined by using the Doppler effect?

I.	The speed at which a star is moving away from an observer.
II.	The transverse velocity of a star.
III.	The radial velocity of a star.
IV.	The speed at which a car is traveling toward an observer.

a.	I & IV
b.	II & III
c.	II & IV
d.	I & III
e.	I, III, & IV

16. Why don't we see hydrogen Balmer lines in the spectra of stars with temperatures of 3,200 K?

a.	There is no hydrogen in stars this cool.
b.	The stars are hot enough that most of the hydrogen is ionized and the atoms can not absorb energy.
c.	These stars are so cool that nearly all of the electrons in the hydrogen atom are in the ground state.
d.	Stars of this temperature are too cool to produce an absorption spectrum.
e.	Stars of this temperature are too hot to produce an absorption spectrum.

17. Why don't we see hydrogen Balmer lines in the spectra of stars with temperatures of 45,000 K?

a.	There is no hydrogen in stars this hot.
b.	The stars are hot enough that most of the hydrogen is ionized and the atoms can not absorb energy.
c.	These stars are so cool that nearly all of the electrons in the hydrogen atom are in the ground state.
d.	Stars of this temperature are too cool to produce an absorption spectrum.
e.	Stars of this temperature are too hot to produce an absorption spectrum.

18. The absorption lines in the visible portion of the spectrum of a star that are produced by hydrogen are from the

a.	Lyman series.
b.	Balmer series.
c.	Paschen series.
d.	isotopes of hydrogen.
e.	ions of hydrogen.

19. The diagram below illustrates a light source, a gas cloud, and three different lines of sight. �Along which line of sight would an observer see an absorption spectrum?

a.	1
b.	2
c.	3
d.	2 and 3
e.	none of them

20. The diagram below illustrates a light source, a gas cloud, and three different lines of sight. �Along which line of sight would an observer see an continuous spectrum?

a.	1
b.	2
c.	3
d.	2 and 3
e.	none of them

21. The diagram below illustrates a light source, a gas cloud, and three different lines of sight. �Along which line of sight would an observer see an emission spectrum?

a.	1
b.	2
c.	3
d.	2 and 3
e.	none of them

22. The table below lists the spectral types for each of five stars. �Which star in this table would have the lowest surface temperature?

Star Name	Spectral Type
a For	F8
o Cet	M7
35 Ari	B3
g Tri	A0
x Per	O7

a.	a For
b.	o Cet
c.	35 Ari
d.	g Tri
e.	x Per

23. The table below lists the spectral types for each of five stars. �Which star in this table would have the greatest surface temperature?

Star Name	Spectral Type
a For	F8
o Cet	M7
35 Ari	B3
g Tri	A0
x Per	O7

a.	a For
b.	o Cet
c.	35 Ari
d.	g Tri
e.	x Per

24. The radiation emitted from a star has a maximum intensity at a wavelength of 300 nm. �What is the temperature of this star?

a.	300 K
b.	100 K
c.	900,000,000 K
d.	90,000 K
e.	10,000 K

25. At what wavelength would a star radiate the greatest amount of energy if the star has a surface temperature of 60,000 K?

a.	50 nm
b.	500 nm
c.	300 nm
d.	1. 8 x 1011 nm
e.	180 nm

26. The sun has a surface temperature of approximately 5800 K. �At what wavelength does the maximum energy radiated by the sun occur?

a.	5800 nm
b.	300 nm
c.	174 nm
d.	520 nm
e.	3000 nm

27. One star has a temperature of 30,000 K and another star has a temperature of 6,000 K Compared to the cooler star, how much more energy per second will the hotter star radiate from each square meter of its surface?

a.	5 times
b.	25 times
c.	8. 1 x 1017 times
d.	625 times
e.	1. 3 x 1015 times

28. One star has a temperature of 10,000 K and another star has a temperature of 5,000 K. �Compared to the cooler star, how much more energy per second will the hotter star radiate from each square meter of its surface?

a.	16 times
b.	2 times
c.	1 x 1016 times
d.	625 times
e.	25 times

29. How much energy is radiated each second by one square meter of a star whose temperature is 10,000 K? s in the Stefan-Boltzmann law is equal to ,

a.	5. 67 x 10 12 J
b.	5. 67 x 10 8 J
c.	5. 67 x 10 4 J
d.	300 nm
e.	300,000,000 nm

30. The H _d line has a wavelength of 410. 2 nm when observed in the laboratory. �If the H _d line appears in a stars spectrum at 410. 0 nm, what is the radial velocity of the star?

a.	146 km/sec away from the observer.
b.	146 km/sec toward the observer.
c.	6. 0 x 10 7 m/sec away from the observer.
d.	6. 0 x 10 7 m/sec toward the observer.
e.	The radial velocity of the star can not be determined from this information.

31. The H g line has a wavelength of 434. 0 nm when observed in the laboratory. �If the Hg line appears in a stars spectrum at 434. 5 nm, what is the radial velocity of the star?

a.	346 km/sec away from the observer.
b.	346 km/sec toward the observer.
c.	1. 3 x 10 8 m/sec away from the observer.
d.	1. 3 x 10 8 m/sec toward the observer.
e.	The radial velocity of the star can not be determined from this information.

32. The binding energy of the first level in an atom is 2. 2 x 10 ^-18 J, and the binding energy of the second energy level is 1. 6 x 10 ^-18 J. �What is the energy of the photon that is emitted if an electron moves from the second level to the first?

a.	3. 3 x 10 -18 J
b.	3. 5 x 10 -36 J
c.	1. 4 J
d.	3. 5 x 10 -18 J
e.	6. 0 x 10 -19 J

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Source: https://commons.wvc.edu/rdawes/ASTR217/Homeworks/HW5/HW5.htm

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