Question 1

The Chandra X-ray Observatory must operate in space because

Accepted Answer

X-rays do not penetrate Earth's atmosphere, so a space-based telescope like the Chandra X-ray Observatory is necessary to study X-ray sources in the universe.

Question 2

How does the light-collecting area of an 8-meter telescope compare to that of a 2-meter telescope?

Accepted Answer

The light-collecting area of a telescope is proportional to the square of its diameter. Therefore, the light-collecting area of the 8-meter telescope is (8/2)^2= 16 times that of the 2-meter telescope. So, the correct answer is A.

Question 3

The diagram represents energy levels in a hydrogen atom. The labeled transitions (A through E) represent an electron moving between energy levels. Which labeled transition represents an electron that absorbs a photo with 10.2 eV of energy?

Accepted Answer

Transition A represents an electron absorbing a photon with 10.2 eV of energy.

Question 4

Which of the following statements about X-rays and radio waves is not true?

Accepted Answer

X-rays and radio waves both travel at the speed of light, so they have the same speed in space. Therefore, statement A is incorrect.

Question 5

Which of the following is always true about images captured with X-ray telescopes?

Accepted Answer

The answer of Which of the following is always true...

Question 6

Which of the following is not an advantage of the Hubble Space Telescope over ground-based telescopes?

Accepted Answer

The Hubble Space Telescope is actually farther away from the stars than ground-based telescopes, but it still has advantages such as the ability to observe without interference from Earth's atmosphere, the capability to observe in multiple wavelengths, and never having to close due to weather conditions.

Question 7

Which of the following conditions lead you to see an absorption line spectrum from a cloud of gas in interstellar space?

Accepted Answer

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Question 8

The angular separation of two stars is 0.1 arcseconds and you photograph them with a telescope that has an angular resolution of 1 arcsecond. What will you see?

Accepted Answer

The telescope's angular resolution is not sufficient to distinguish between the two stars, so they will appear as a single point of light.

Question 9

What is the purpose of interferometry?

Accepted Answer

Interferometry allows two or more small telescopes to achieve the angular resolution of a much larger telescope by combining their signals and creating an interference pattern. This technique improves the resolution of astronomical observations and helps scientists study details of celestial objects that would otherwise be impossible to observe with a single telescope.

Question 10

Which of the following statements about thermal radiation is always true?

Accepted Answer

The answer of Which of the following statements about thermal...

Question 11

The diagram represents energy levels in a hydrogen atom. The labeled transitions (A through E. represent an electron moving between energy levels. Suppose that an electron in a hydrogen atom absorbs 10.2 eV of energy, so that it moves from level 1 to level 2. What typically happens next?

Accepted Answer

When an electron absorbs energy and moves to a higher energy level, it is said to be in an excited state. The electron will eventually lose this energy and return to its original energy level. This typically happens through the emission of a photon (a particle of light) with the same amount of energy as the original absorption. In this case, the electron would emit an ultraviolet photon with 10.2 eV of energy when it returns to level 1, as described in choice A. Choices B and C are not accurate representations of how electron energy levels work in atoms. Choice D is also incorrect, as electrons in atoms are not interchangeable in this way.

Question 12

Studying a spectrum from a star can tell us a lot. All of the following statements are true except one. Which statement is not true?

Accepted Answer

The total amount of light in the spectrum does not tell us the star's radius. The star's radius can be inferred from other measurements, such as its luminosity and temperature.

Question 13

Laboratory measurements show hydrogen produces a spectral line at a wavelength of 486.1 nanometers (nm). A particular star's spectrum shows the same hydrogen line at a wavelength of 486.0 nm. What can we conclude?

Accepted Answer

The observed wavelength is slightly shorter than the laboratory measurement, indicating a blueshift. This suggests the star is moving toward us.

Question 14

Each of the following describes an "Atom 1" and an "Atom 2." In which case are the two atoms different isotopes of the same element?

Accepted Answer

Atom 1 and Atom 2 have the same number of protons (7) but different numbers of neutrons. This means they are different isotopes of the same element, which in this case is nitrogen (N) since it has 7 protons.

Question 15

Suppose that Star X and Star Y both have redshifts, but Star X has a larger redshift than Star Y. What can you conclude?

Accepted Answer

Redshift is a measure of how much the light from an object is stretched as it travels through space. The greater the redshift, the faster the object is moving away from us. Therefore, if Star X has a larger redshift than Star Y, we can conclude that Star X is moving away from us faster than Star Y.

Question 16

Which of the following best describes why we say that light is an electromagnetic wave?

Accepted Answer

Electromagnetic waves are characterized by the waveform that forms when electric and magnetic fields oscillate perpendicular to one another. When light travels, it creates an oscillating electric field (E) perpendicular to an oscillating magnetic field (B). The movement of these fields can cause electrically charged particles to move up and down, creating a wave of electromagnetic energy.

Question 17

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

In a scale-model atom where the nucleus is the size of a tennis ball, the electron cloud would extend several kilometers, reflecting the vast empty space within an atom compared to the size of the nucleus.

Question 18

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 red color in a star typically indicates that its surface temperature is cooler than the Sun. Hotter stars appear blue or white, while cooler stars appear red.

Question 19

Which of the following statements is true of green grass?

Accepted Answer

Green grass appears green because it absorbs most of the colors in white light, such as red and blue, but reflects green light. Therefore, option A is the correct statement. Option B is incorrect because grass does not emit light, and options C and D are also incorrect as grass does not transmit any color selectively and does not necessarily indicate health.

Quiz 5: Light: the Cosmic Messenger