Question 1

The resolution of a 10- meter telescope is about 0.01 arcsecond for visible light. Would you expect the actual angular resolution of a Keck 10- meter telescope in Hawaii to be better than, equal to, or worse than 0.01 arcsecond? Explain.

Accepted Answer

It would be worse th...

Question 2

A gas heated to millions of degrees would emit

Accepted Answer

A)  an equal amount of all wavelengths of light.
B)  no light, because it is too hot.
C)  mostly ultraviolet light.
D)  mostly X- rays.
E)  mostly radio waves.

Question 3

The frequency of a wave is

Accepted Answer

A)  the number of peaks passing by any point each second.
B)  equal to the speed of the wave divided by the wavelength of the wave.
C)  measured in cycles per second.
D)  measured in hertz (Hz) .
E)  all of the above

Question 4

The energy levels of an element and its ions are the same.

Accepted Answer

A) True 
 B)False

Question 5

Imagine that the sun ceased emitting light at wavelengths from about 600 to 700 nm. How would this look to us, and why?

Accepted Answer

The sun would appear blue- gre...

Question 6

Doppler shifted hydrogen absorption lines are seen in the spectrum of a star. The hydrogen line at 656.28 nm is seen to be shifted to 656.08 nm. How fast is the star moving (Note: The speed of light is approximately 300,000 km/s, or 3 × 105 km/s.) ?

Accepted Answer

A)  about 1,000 km/s
B)  about 10,000 km/s
C)  about 100 km/s
D)  about 1,000,000 km/s

Question 7

From shortest to longest wavelength, which of the following correctly orders the different categories of electromagnetic radiation?

Accepted Answer

A)  gamma rays, X- rays, visible light, ultraviolet, infrared, radio
B)  gamma rays, X- rays, ultraviolet, visible light, infrared, radio
C)  radio, infrared, visible light, ultraviolet, X- rays, gamma rays
D)  infrared, visible light, ultraviolet, X- rays, gamma rays, radio

Question 8

Which of the following would be the most capable ultraviolet telescope?

Accepted Answer

A)  a 30 meter telescope, on a mountain
B)  a 10 meter telescope, on a mountain
C)  a 2.5 meter telescope, in space
D)  a 4 meter telescope, in space

Question 9

The Chandra X- ray Observatory must operate in space because

Accepted Answer

A)  X- rays are too dangerous to be allowed on the ground.
B)  X- ray telescopes require the use of grazing incidence mirrors.
C)  It was built by NASA.
D)  X- rays do not penetrate Earth's atmosphere.

Question 10

Betelgeuse is the bright red star representing the left shoulder of the constellation Orion. All the following statements about Betelgeuse are true. Which one can you infer from its red color?

Accepted Answer

A)  It is much brighter than the Sun.
B)  It is much more massive than the Sun.
C)  It is moving away from us.
D)  Its surface is cooler than the surface of the Sun.

Question 11

An atomic nucleus has a size of about

Accepted Answer

A)  10- 15 meters.
B)  10- 12 meters.
C)  10- 6 meters.
D)  10- 9 meters.

Question 12

Suppose you built a scale- model atom in which the nucleus is the size of a tennis ball. About how far would the cloud of electrons extend?

Accepted Answer

A)  a few meters
B)  to the Sun
C)  several centimeters
D)  several kilometers

Question 13

One star is emitting primarily visible light and another star is emitting primarily infrared light. Which star is hotter?

Accepted Answer

A)  the star emitting infrared light
B)  the star emitting visible light
C)  Both stars are the same temperature.
D)  The temperature also depends on the radius of the star, so one can't decide based on the information provided.

Question 14

White light hitting white paper is an example of

Accepted Answer

A)  reflection or scattering.
B)  emission.
C)  absorption.
D)  transmission.

Question 15

Any object moving towards or away from the Earth will show a Doppler shift when observed from Earth.

Accepted Answer

A) True 
 B)False

Question 16

If a material is transparent, then it

Accepted Answer

A)  scatters light well.
B)  reflects light well.
C)  absorbs light well.
D)  emits light well.
E)  transmits light well.

Question 17

Which of the following is an example of reflection or scattering?

Accepted Answer

A)  Visible light does not pass through a black wall.
B)  Light comes from your computer screen.
C)  Blue light hits a red sweatshirt.
D)  Red light hits a red sweatshirt.

Question 18

In what part of the electromagnetic spectrum do the biggest telescopes on Earth operate?

Accepted Answer

A)  X- ray
B)  visible
C)  infrared
D)  ultraviolet
E)  radio

Question 19

An atom that has fewer electrons than protons is called a(n) .

Accepted Answer

A)  ion
B)  solid
C)  plasma
D)  molecule

Question 20

Explain why an absorption line spectrum is not filled back in (to make the original continuous spectrum)by the photons that are emitted as the excited electrons decay back down to their original energy levels.

Accepted Answer

The photons emitted by the dec...

Exam 5: Light: the Cosmic Messenger

The resolution of a 10- meter telescope is about 0.01 arcsecond for visible light. Would you expect the actual angular resolution of a Keck 10- meter telescope in Hawaii to be better than, equal to, or worse than 0.01 arcsecond? Explain.

Correct AnswerverifiedIt would be worse th...View AnswerShow Answer

Any object moving towards or away from the Earth will show a Doppler shift when observed from Earth.

Correct AnswerverifiedShow Answer

If a material is transparent, then it

Correct AnswerverifiedShow Answer

Imagine that the sun ceased emitting light at wavelengths from about 600 to 700 nm. How would this look to us, and why?

Correct AnswerverifiedThe sun would appear blue- gre...View AnswerShow Answer

An atom that has fewer electrons than protons is called a(n) .

Correct AnswerverifiedShow Answer

From shortest to longest wavelength, which of the following correctly orders the different categories of electromagnetic radiation?

Correct AnswerverifiedShow Answer

Doppler shifted hydrogen absorption lines are seen in the spectrum of a star. The hydrogen line at 656.28 nm is seen to be shifted to 656.08 nm. How fast is the star moving (Note: The speed of light is approximately 300,000 km/s, or 3 × 105 km/s.) ?

Correct AnswerverifiedShow Answer

The frequency of a wave is

Correct AnswerverifiedShow Answer

Explain why an absorption line spectrum is not filled back in (to make the original continuous spectrum)by the photons that are emitted as the excited electrons decay back down to their original energy levels.

Correct AnswerverifiedThe photons emitted by the dec...View AnswerShow Answer

In what part of the electromagnetic spectrum do the biggest telescopes on Earth operate?

Correct AnswerverifiedShow Answer

Betelgeuse is the bright red star representing the left shoulder of the constellation Orion. All the following statements about Betelgeuse are true. Which one can you infer from its red color?

Correct AnswerverifiedShow Answer

The energy levels of an element and its ions are the same.

Correct AnswerverifiedShow Answer

The Chandra X- ray Observatory must operate in space because

Correct AnswerverifiedShow Answer

Suppose you built a scale- model atom in which the nucleus is the size of a tennis ball. About how far would the cloud of electrons extend?

Correct AnswerverifiedShow Answer

A gas heated to millions of degrees would emit

Correct AnswerverifiedShow Answer

Which of the following would be the most capable ultraviolet telescope?

Correct AnswerverifiedShow Answer

An atomic nucleus has a size of about

Correct AnswerverifiedShow Answer

One star is emitting primarily visible light and another star is emitting primarily infrared light. Which star is hotter?

Correct AnswerverifiedShow Answer

Which of the following is an example of reflection or scattering?

Correct AnswerverifiedShow Answer

White light hitting white paper is an example of

Correct AnswerverifiedShow Answer

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It would be worse th...
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The sun would appear blue- gre...
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The photons emitted by the dec...
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