Question 1

A telescope with a diameter of 2 m is just barely able to resolve features on a gas cloud when observing it at 500 nm wavelength.Which of the following observations would also just barely be able to resolve these features?
A) a 1-m diameter telescope observing at 1,000 nm
B) a 4-m diameter telescope observing at 125 nm
C) a 4-m diameter telescope observing at 250 nm
D) a 1-m diameter telescope observing at 250 nm

Accepted Answer

The answer of A telescope with a diameter of 2...

Question 2

A rubber ball falls from a height of 1,000 m,accelerates,and then impacts Earth.During the impact,it heats up so much that it melts.The melted rubber glows and eventually cools off.How would you describe the flow of energy in this scenario?

Accepted Answer

The answer of A rubber ball falls from a height...

Question 3

A reading light contains a dimmer switch that can vary its luminosity from 10 W to 100 W.If the device produces just the right amount of light when set to 10 W and held at a distance of 10 centimeters,to what value should you set the wattage if you hold it 20 centimeters away?

Accepted Answer

The answer of A reading light contains a dimmer switch...

Question 4

Modern astronomical observatories sometimes shine lasers into the sky because they:
A) help guide the pointing of the telescope.
B) allow corrections of atmospheric turbulence.
C) decrease the atmospheric opacity.
D) calibrate spectroscopes.

Accepted Answer

Shining lasers into the sky can allow astronomers to measure and correct for atmospheric turbulence, which can cause distortions in astronomical images. This technique is known as adaptive optics and is used to improve the resolution and clarity of images obtained from telescopes on the ground.

Question 5

What does thermal energy represent?

Accepted Answer

The answer of What does thermal energy represent?...

Question 6

An astronomer takes spectra of two stars,A and B.Star A's spectrum peaks at 200 nm,while star B's spectrum peaks at 800 nm.If the stars have identical sizes,how do their luminosities compare?

Accepted Answer

The answer of An astronomer takes spectra of two stars,A...

Question 7

An astronomer takes spectra of two stars,A and B.She discovers that the continuous part of star A's spectrum peaks at 200 nm,while the continuous part of star B's spectrum peaks at 800 nm.Both stars have dark bands superposed on this continuous spectrum,and the locations of these dark bands are the same in both stars.What do you know about the composition of the stars? Why?

Accepted Answer

The answer of An astronomer takes spectra of two stars,A...

Question 8

Which of the following portions of the electromagnetic spectrum must be observed from space?
A) ultraviolet
B) radio
C) near infrared
D) visible

Accepted Answer

Ultraviolet radiation is absorbed by Earth's atmosphere, so it can only be observed from space. Radio waves, near infrared and visible light can also be observed from Earth's surface.

Question 9

How would you use a star's spectrum to measure its temperature?

Accepted Answer

The answer of How would you use a star's spectrum...

Question 10

A pair of radio dishes,each with collecting area 100 m²,lie a distance of 10 km from each other.With them,astronomers can make a measurement with an effective collecting area of ________ and an effective angular resolution of a telescope with a ________ diameter. A) 10⁸ m²; 200 m B) 10⁸ m²; 200 m. C) 200 m²; 10 km D) 200 m²; 10 km.

Accepted Answer

The effective collecting area is the sum of the two dishes, which is 200 m². The effective angular resolution is determined by the distance between the dishes, which is 10 km.

Question 11

The Chandra X-Ray Observatory achieves high angular resolution with:
A) interferometry.
B) a large diameter aperture.
C) grazing incidence mirrors.
D) lead plates that block unwanted X-rays.

Accepted Answer

Chandra achieves high angular resolution using grazing incidence mirrors. These mirrors are coated with a thin layer of iridium and are arranged in nested shells to focus incoming X-rays onto the detector. This design allows for high resolution imaging and sensitivity to low levels of X-ray emission. The other options (A, B, and D) do not directly contribute to the Chandra Observatory's high angular resolution.

Question 12

Consider the experiment shown in the figure below.Describe the spectra observed by Spectrographs A,B,and C.

Accepted Answer

The answer of Consider the experiment shown in the figure...

Question 13

Which of the following sites would make the best location for an infrared telescope?
A) the South Pole
B) a deep valley
C) an arctic mountain
D) a high-altitude desert

Accepted Answer

A high-altitude desert would make the best location for an infrared telescope as it offers clear and dry skies, with little atmospheric interference from water vapor and pollution, which would allow for the best observation of infrared light from celestial objects.

Question 14

Type I supernovae all have (nearly)identical luminosities.Explain how this fact allows us to measure their distances.

Accepted Answer

The answer of Type I supernovae all have (nearly)identical luminosities.Explain...

Question 15

The practice of combining signals from two or more reflectors to achieve better angular resolution is:
A) adaptive optics.
B) interferometry.
C) refraction.
D) signal processing.

Accepted Answer

Interferometry is the practice of combining signals from two or more reflectors to achieve better angular resolution. It allows for more precise measurement and imaging of distant objects, such as in radio astronomy or medical imaging. Adaptive optics, refraction, and signal processing are all related techniques, but do not involve the combination of multiple reflectors in the same way as interferometry.

Question 16

Which of the following types of light has the highest atmospheric transmission?
A) radio
B) infrared
C) ultraviolet light
D) gamma rays

Accepted Answer

Radio waves have the highest atmospheric transmission as they have the longest wavelength and the lowest frequency, and can easily pass through the atmosphere without interacting with the molecules in the air. In contrast, gamma rays have the shortest wavelength and highest frequency and are easily absorbed by the atmosphere, while ultraviolet (UV) light and infrared (IR) radiation are partially absorbed by the atmosphere, reducing their transmission.

Question 17

List the seven components of the electromagnetic spectrum from shortest to longest wavelength.

Accepted Answer

The answer of List the seven components of the electromagnetic...

Question 18

A particular water wave has an amplitude of 2 m and a wavelength of 3 m.With this wave,the time between successive crests hit shore is 2 seconds.What is the speed of the wave?

Accepted Answer

The answer of A particular water wave has an amplitude...

Question 19

An astronomer using a refracting telescope sees an image of two gas clouds with identical shapes but displaced slightly from each other.One is composed of blue light and the other red light.The most likely explanation is:
A) the Doppler effect.
B) chromatic aberration.
C) dust absorption.
D) interstellar scattering.

Accepted Answer

Chromatic aberration occurs because lenses have different refractive indices for light of different colors, causing them to be focused at slightly different positions. This leads to images with color fringes or images of different colors being displaced from each other, as described in the scenario.

Question 20

Stars twinkle because of:
A) interstellar dust.
B) surface variations on the stars.
C) atmospheric turbulence.
D) opacity variations.

Accepted Answer

Stars appear to twinkle or shimmer in the night sky because of atmospheric turbulence. The Earth's atmosphere consists of layers of varying temperature and density, which bend and refract the light passing through them at different angles. As the light from a star enters the atmosphere, it gets refracted and bent multiple times, leading to tiny variations in its apparent position and intensity on the observer's retina. This random motion of light rays creates the effect of twinkling or scintillation, which is most noticeable when a star is low in the sky, or when its light passes through more layers of atmosphere.

Quiz 4: A Universe of Universal Laws

A telescope with a diameter of 2 m is just barely able to resolve features on a gas cloud when observing it at 500 nm wavelength.Which of the following observations would also just barely be able to resolve these features?

A rubber ball falls from a height of 1,000 m,accelerates,and then impacts Earth.During the impact,it heats up so much that it melts.The melted rubber glows and eventually cools off.How would you describe the flow of energy in this scenario?

A reading light contains a dimmer switch that can vary its luminosity from 10 W to 100 W.If the device produces just the right amount of light when set to 10 W and held at a distance of 10 centimeters,to what value should you set the wattage if you hold it 20 centimeters away?

Modern astronomical observatories sometimes shine lasers into the sky because they:

What does thermal energy represent?

An astronomer takes spectra of two stars,A and B.Star A's spectrum peaks at 200 nm,while star B's spectrum peaks at 800 nm.If the stars have identical sizes,how do their luminosities compare?

Which of the following portions of the electromagnetic spectrum must be observed from space?

How would you use a star's spectrum to measure its temperature?

A pair of radio dishes,each with collecting area 100 m²,lie a distance of 10 km from each other.With them,astronomers can make a measurement with an effective collecting area of and an effective angular resolution of a telescope with a diameter.

The Chandra X-Ray Observatory achieves high angular resolution with:

Consider the experiment shown in the figure below.Describe the spectra observed by Spectrographs A,B,and C.

Which of the following sites would make the best location for an infrared telescope?

Type I supernovae all have (nearly)identical luminosities.Explain how this fact allows us to measure their distances.

The practice of combining signals from two or more reflectors to achieve better angular resolution is:

Which of the following types of light has the highest atmospheric transmission?

List the seven components of the electromagnetic spectrum from shortest to longest wavelength.

A particular water wave has an amplitude of 2 m and a wavelength of 3 m.With this wave,the time between successive crests hit shore is 2 seconds.What is the speed of the wave?

An astronomer using a refracting telescope sees an image of two gas clouds with identical shapes but displaced slightly from each other.One is composed of blue light and the other red light.The most likely explanation is:

Stars twinkle because of: