1. When used at a wavelength of 1 micron, a telescope can resolve angles as small as 0.1 seconds of arc. How small an angle could the telescope resolve when used at a wavelength of 5 microns?
a. 0.02 seconds of arc
b. 0.004 seconds of arc
c. 0.5 seconds of arc
d. 0.25 seconds of arc
1. Which of the following is not likely to be an attribute of a good observing site?
a. dark sky
b. atmospheric stability
c. low elevation
d. low humidity
1. Telescope A has a mirror that is 10 times larger than the mirror of telescope B. Telescope A can resolve an angle as small as 0.1 seconds of arc. What is the smallest angle that can be resolved by telescope B?
a. 10 seconds of arc
b. 1 second of arc
c. 0.1 second of arc
d. 0.01 second of arc
1. Radio astronomers obtain great angular resolution by
a. observing at the longest wavelength possible.
b. using arrays of radio telescopes
c. observing objects when they are near the horizon.
d. observing an object with the same radio telescope for many years.
1. Which of the following kinds of photons are least energetic?
1. How does the light-gathering power of a 40 cm telescope compare to that of a 20 cm telescope?
a. they are the same
b. 2 times as great
c. 4 times as great
d. 8 times as great
1. In the laboratory, a spectral line of an element has a wavelength of 5000 Angstroms. What would be the measured wavelength of that line in the spectrum of a planet which is approaching at a velocity of 30 km/s? (The speed of light is 300,000 km/s.)
a. 4999.5 Angstroms
b. 4995 Angstroms
c. 5000.5 Angstroms
d. 5005 Angstroms
1. In the laboratory, an atom emits a spectral line at a wavelength of 400 nanometers. In the spectrum of a star, the same spectral line is found to have a wavelength of 410 nanometers. What can be said about the star?
a. It is hotter than the Sun.
b. It is moving toward the Earth.
c. It is moving away from the Earth
d. It contains elements that are not found on Earth.
1. A star is moving away from an observer at 1% of the speed of light. At what wavelength would the observer find an emission line which would occur at a wavelength of 6000 Angstroms if the star were at rest?
a. 6060 Angstroms
b. 6010 Angstroms
c. 6000 Angstroms
d. 5940 Angstroms
1. A TV satellite broadcasts at a frequency of 5000 MHz, (1 MHz = 1 million Hertz). What is the wavelength of this radiation?
a. 1000 cm
b. 5 million centimeters
c. 6 cm
d. 0.3 cm
1. The wavelength of a wave is 2 meters. The frequency of the wave is 2 Hz. What is the speed of the wave?
a. 16 m/s
b. 4 m/s
c. 64 m/s
d. 0.25 m/s
1. Which of the following forms of electromagnetic radiation has the longest wavelength?
1. The same telescope is used to obtain an image using light of the following wavelengths. Which of the images will have the poorest angular resolution?
1. Which of the following is true about the frequency and velocity of electromagnetic waves?
a. The product of frequency and wavelength is the same for all such waves.
b. As frequency increases, wavelength increases.
c. Frequency is constant for all wavelengths.
d. Frequency and wavelength are independent of each other.
1. A particle of light is a
1. Compared with infrared waves, radio waves
a. have higher energy.
b. are lower frequency.
c. take much longer to reach us from celestial objects.
d. have shorter wavelengths.
1. How does the speed of light in glass compare to the speed of light in a vacuum?
a. It is larger in glass.
b. It is larger in a vacuum.
c. Trick question, light can't travel in glass.
d. They are the same.
1. A telescope that uses a lens to bring radiation to a primary focus is called a:
a. radio telescope.
1. How many 4 meter telescopes would be required to match the light gathering power of a 16 meter telescope?
1. The focal ratio of a lens or mirror is the ratio of its
a. focal length to diameter.
b. diameter to thickness.
c. magnification to diameter.
d. focal length to thickness.
1. Which of the following forms of electromagnetic waves (or photons) has the greatest energy?
1. Which of the following are NOT electromagnetic waves?
a. radio waves
b. optical light
d. gravitational waves
1. Why do X-ray telescopes have to be placed in space satellites?
a. They are too sensitive to terrestial radiation.
b. They are too dangerous for astronomers to operate on the ground.
c. The Earth's atmosphere absorbs cosmic Xrays.
d. There is too much scattered sunlight in the Earth's atmosphere.
e. The mirrors for X-ray telescopes are too large to operate on ground.
1. Suppose a source of electromagnetic waves is moving toward us at 2% of the speed of light. What can be said of the wavelength of the waves we receive from the source?
a. They are blueshifted by 2%.
b. They are redshifted by 2%.
c. They are blueshifted by 4%.
d. They are redshifted by 4%.
1. The product of the wavelength and frequency of a wave is equal to
a. the speed of the wave.
b. the energy of the wave.
c. the distance between crests of the wave.
d. the temperature of the wave.
1. Suppose you want to determine if there is any methane gas on a newly discovered planet. You need to equip your telescope with a
b. photographic plate holder.
d. space probe can't determine anything about gases without travelling there.
1. At what wavelength will the spectrum of a perfect black body with a temperature of 6,204 Kelvin peak, assuming that a perfect black body at 6000 Kelvin has a spectrum that peaks exactly at 500 nm? Express your answer in nm to the nearest whole nm. (Use the values given in this question to calculate your answer...)
1. An "isotope" is a nucleus:
a. ...which carries no net charge.
b. ...with a number of neutrons added or removed.
c. ...which cannot absorb radiation.
d. ...with a number of protons added or removed.
e. ...which carries a net charge.
1. Star A has 2 times the surface temperature and 0.8 times the radius of Star B. What is the ratio of the luminosity of Star A to the luminosity of Star B? (Indicate your answer to an accuracy of 0.1).
1. If a star is receding (moving away from us) at a speed of 1% of the speed of light, at what wavelength would a spectral line with a laboratory wavelength of 459 nm be observed? Express your answer in nm to the nearest 0.1 nm.
1. An "ion" is an atom or molecule:
a. ...with a number of neutrons added or removed.
b. ...with a number of protons added or removed to the nucleus.
c. ...which cannot absorb radiation.
d. ...which carries a net charge.
e. ...which carries no net charge.
This material may consist of step-by-step explanations on how to solve a problem or examples of proper writing, including the use of citations, references, bibliographies, and formatting. This material is made available for the sole purpose of studying and learning - misuse is strictly forbidden.1. c. 0.5 seconds of arc
2. c. low elevation
3. b. 1 second of arc
4. b. using arrays of radio telescopes
5. a. infrared...