Why do astronomers build radio telescopes?
Radio waves give a different view of the universe
Radio waves from space reach the Earth’s surface
Radio telescopes can detect signals from aliens
Radio telescopes can be much larger than optical telescopes
What type of telescope is most likely to suffer from chromatic aberration and have a low light-gathering power?
a small diameter reflecting telescope
a large diameter reflecting telescope
a small diameter refracting telescope
a large diameter refracting telescope
When does chromatic aberration occur in a telescope?
when different colours of light do not focus at the same point in a reflecting telescope
when different colours of light do not focus at the same point in a refracting telescope
when light of different wavelengths gets absorbed by the mirror in a reflecting telescope
when light of different wavelengths gets absorbed by the lens in a refracting telescope
What type of telescope is a radio telescope?
reflecting
refracting
deflecting
retracting
What type of telescope has a lens as its objective and contains no mirrors?
compound
How is the objective of most radio telescopes similar to the objective of a reflecting optical telescope?
They are both bowl-shaped (concave)
They are both hill-shaped (convex)
They are typically the same size
They are both made of metal
What type of primary is found in a reflecting telescope?
prism
mirror
lens
diffraction grating
You point your backyard reflecting telescope at the star Vega. Where does Vega’s light go?
from the primary mirror, to the secondary mirror, to the eyepiece
from the primary mirror to the eyepiece
through the primary lens, to the secondary mirror, to the eyepiece
through the primary lens, through the secondary lens, to the eyepiece
Which of the following best explains the concept of atmospheric windows?
Holes in the Earth’s atmosphere allow ultraviolet radiation to reach the North and South poles
X-ray radiation from space can see through the atmosphere to observe activities on the ground
Only certain wavelengths of electromagnetic radiation from space reach the Earth’s surface
The Earth’s atmosphere can be “closed” or “open” to electromagnetic radiation, depending on the weather
What is the main reason for building large optical telescopes?
It’s the best way to see through clouds and other light-absorbers in the atmosphere
It’s the best way to collect as much light as possible from faint objects
It’s the best way to nullify the blurring effects of the Earth’s atmosphere and thus produce higher resolution images
It’s the best way to magnify objects and make them brighter
An astronomer takes two pictures of the same object using the Hubble Space Telescope. One picture is taken with red light and one with blue light. Which one would you expect to show finer details?
Blue light will show finer details
Red light will show finer details
Both should be the same
The amount of detail depends on the distance to the object
Which property of a telescope determines its light-gathering power?
the focal length of the objective
the focal length of the eyepiece
the diameter of the objective
the length of the telescope tube
What is the light-gathering power of a telescope directly proportional to?
the diameter of the primary mirror or lens
the focal length of the primary mirror or lens
the diameter of the eyepiece
Why can’t a telescope image be magnified to show any level of detail?
Diffraction limits the amount of detail that is visible
Telescopes only view a small region of the sky
Magnification depends on focal length
Resolving power depends on wavelength
Which of the following has the most light-gathering power?
a telescope of 5 centimeters diameter and focal length of 50 centimeters
a telescope of 6 centimeters diameter and focal length of 100 centimeters
a telescope of 2 centimeters diameter and focal length of 100 centimeters
a telescope of 3 centimeters diameter and focal length of 75 centimeters
How is the resolving power of a telescope defined?
It is a measure of the minimum angular separation that can be seen with the telescope
It is a measure of the amount of light that the telescope can gather in one second
It is the separation between the objective and the image
It is a measure of how blurry objects appear in the telescope
What happens to a telescope’s light-gathering power and resolving power when you increase its diameter?
Its light-gathering power and resolving power both increase
Its light-gathering power increases and its resolving power decreases
Its light-gathering power decreases and its resolving power increases
Its light-gathering power and resolving power both decrease
What can be done to improve the resolving power of ground-based optical telescopes?
Use them at longer wavelengths
Equip them with an adaptive optics system
Change them from reflectors to refractors
Increase their focal length
The pupil of the human eye is approximately 0.8 centimeters in diameter when adapted to the dark. What is the ratio of the light-gathering power of a 1.6 meter telescope to that of the human eye?
2 : 1
20 : 1
400 : 1
40,000 : 1
What is the ratio of the light-gathering power of a 10-metre telescope to that of a 1-metre telescope?
10 to 1
1 to 10
100 to 1
1 to 100
The diagram below illustrates the layout and light path of a reflecting telescope of the __________design
A(n)___________is used to measure the brightness and colour of stars
300 nanometer light has a lower frequency than 500 nanometer light
X-rays easily penetrate the Earth’s atmosphere and reach the ground from space
What is the purpose of interferometry?
It is used to improve the resolving power of telescopes
It is used to decrease the chromatic aberration of a telescope
It is used to make large X-ray and ultraviolet telescopes
It allows radio telescopes to be within a few hundred feet of each other
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