Galaxies and Quasars Practice Problems

By — McGraw-Hill Professional
Updated on Sep 18, 2011

Review the following concepts if needed:

Galaxies and Quasars Practice Problems

Refer to the text if necessary. A good score is 8 correct. Answers are in the back of the book.

1. As a black hole pulls more and more matter in,

(a) the Schwarzchild radius increases.

(b) the Schwarzchild radius decreases.

(c) the density increases.

(d) it gets darker and darker.


2. Quasars with large blue shifts in their spectra

(a) are receding from us at nearly the speed of light.

(b) are approaching us at nearly the speed of light.

(c) are never seen.

(d) emit large amounts of x-rays compared with other quasars.


3. When a celestial object scintillates, we can surmise that it

(a) is extremely luminous.

(b) has a small angular diameter.

(c) is a great distance from us.

(d) emits energy mainly at short wavelengths.


4. Radio galaxies

(a) emit far more energy at radio wavelengths than typical galaxies.

(b) emit energy only at radio wavelengths.

(c) have been observed only with radio telescopes.

(d) are those galaxies toward which we have sent radio signals in an attempt to communicate with alien civilizations.


5. If the spectrum of an object is red-shifted, this means that the emission or absorption lines

(a) look red in color when examined visually.

(b) appear at longer wavelengths than normal.

(c) appear at higher frequencies than normal.

(d) are most prominent in the red part of the spectrum.


6. A certain galaxy is observed, and its distance is estimated at 10 Mpc. We see this object as it appeared approximately

(a) 10,000 years ago.

(b) 10 million years ago.

(c) 32,600 years ago.

(d) 32.6 million years ago.


7. Within a cluster of galaxies,

(a) all the galaxies are of the same type.

(b) all the galaxies spin in the same direction.

(c) all the galaxies are approximately the same size.

(d) None of the above


8. Quasars are believed to be much smaller than typical galaxies based on the observation that

(a) they emit large amounts of energy at radio wavelengths.

(b) their spectra are red-shifted.

(c) they are nearby, in the Milky Way galaxy.

(d) they can grow dimmer or brighter in short periods of time.


9. The spiral nebulae are large, distant congregations of stars rather than smaller objects within the Milky Way. In order to determine this, astronomers observed

(a) the colors of the gases comprising them.

(b) the radio emissions produced by them.

(c) the rate at which they spin.

(d) the brightnesses and periods of Cepheid variables within them.


10. A football-shaped galaxy might be classified as

(a) S0.

(b) S2.

(c) E5.

(d) SBc.



1. A

2. C

3. B

4. A

5. B

6. D

7. D

8. D

9. D

10. C

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