Deck 4: Astronomical Telescopes and Instruments

Question 1

What is the term for a piece of glass with many small parallel lines etched on its surface,used to produce a spectrum?

A)grating
B)spectrograph
C)charge-coupled device
D)prism

Answer 1

grating

Question 2

Why do astronomers build telescopes on tops of mountains?

A)There is less air to dim the light.
B)The weather is better on mountain tops.
C)Electronic cameras work better when there is less oxygen in the air.
D)Mountaintops are closer to objects in space.

Answer 2

There is less air to dim the light.

Question 3

What feature of a telescope is a measure of its ability to show fine detail and depends on the diameter of the objective?

A)light-gathering power
B)focal length
C)magnifying power
D)resolving power

Answer 3

resolving power

Question 4

Which feature(s)of a telescope determine its magnifying power?

A)diameter of the primary only
B)focal length of the primary only
C)primary diameter and focal length of the eyepiece
D)focal length of the primary and eyepiece

Question 5

Why must far-infrared astronomy be done from high-flying aircraft or spacecraft?

A)Far-infrared radiation is absorbed low in the Earth's atmosphere.
B)Far-infrared photons are quite energetic.
C)Far-infrared photons have long wavelengths.
D)Far-infrared radiation is reflected from the top of the Earth's atmosphere.

Question 6

Which of the following has a few million light-sensitive diodes in an array typically measuring about one centimetre square?

A)charge-coupled device
B)spectrograph
C)photographic plate
D)grating

Question 7

Which of the following telescope types must be used above the Earth's atmosphere?

A)an optical telescope
B)a refracting telescope
C)an X-ray telescope
D)a radio telescope

Question 8

Why do radio telescopes have poor resolving power?

A)Their diameters are extremely large.
B)The energy they receive is not electromagnetic radiation.
C)Radio waves have long wavelengths.
D)Radio waves travel at slow speeds.

Question 9

Which of the following types of light has wavelengths that are longer than the wavelengths of visible light?

A)gamma rays
B)ultraviolet
C)infrared
D)X-rays

Question 10

Why do astronomers build radio telescopes?

A)Radio waves give a different view of the universe.
B)Radio waves from space reach the Earth's surface.
C)Radio telescopes can detect signals from aliens.
D)Radio telescopes can be much larger than optical telescopes.

Question 11

An astronomy graduate student takes a long-exposure picture with a CCD camera but forgets to turn on the telescope tracking.What will the picture look like?

A)The picture will be blank.
B)The picture will be blurry.
C)The picture will have long, thin star trails.
D)The picture will have many false colours.

Question 12

What is the term for the technique of connecting multiple telescopes together to combine the images from each telescope?

A)resolving power
B)active optics
C)adaptive optics
D)interferometry

Question 13

What is the purpose of interferometry?

A)It is used to improve the resolving power of telescopes.
B)It is used to decrease the chromatic aberration of a telescope.
C)It is used to make large X-ray and ultraviolet telescopes.
D)It allows radio telescopes to be within a few hundred feet of each other.

Question 14

What type of telescope is most likely to suffer from chromatic aberration and have a low light-gathering power?

A)a small diameter reflecting telescope
B)a small diameter refracting telescope
C)a large diameter reflecting telescope
D)a large diameter refracting telescope

Question 15

A new generation of ground-based telescopes are currently being built to overcome the limitations of the older large telescopes.How are these different from previous telescopes?

A)They can eliminate light pollution.
B)They can detect X-rays.
C)They use computers to control the shape of the mirror.
D)They can see through clouds.

Question 16

Which of the following types of radiation from a star cannot penetrate the Earth's atmosphere and reach the ground?

A)ultraviolet
B)visible
C)infrared
D)nuclear

Question 17

How does the energy of a photon relate to the other properties of light?

A)Energy is directly proportional to the wavelength of the light.
B)Energy is inversely proportional to the wavelength of the light.
C)Energy depends only on the speed of the light.
D)Energy is inversely proportional to the frequency of the light.

Question 18

What is the longest wavelength of light that can be seen with the human eye?

A)400 nanometres
B)700 nanometres
C)7000 nanometres
D)3×10⁸ m

Question 19

Which of the following types of light has wavelengths that are shorter than the wavelengths of visible light?

A)gamma rays
B)radio waves
C)infrared radiation
D)microwaves

Question 20

How does long wavelength visible light appear to the average human eye?

A)invisible
B)green
C)blue
D)red

Question 21

Which of the following types of electromagnetic radiation is absorbed by ozone in the Earth's atmosphere?

A)infrared radiation
B)ultraviolet radiation
C)X-ray radiation
D)visible light

Question 22

Radio telescopes are affected by interference from human-made radio devices.What is the equivalent problem for optical telescopes?

A)light pollution
B)seeing
C)clouds and water vapour
D)atmospheric turbulence

Question 23

Which of the following types of electromagnetic radiation has the greatest energy per photon?

A)X-rays
B)radio waves
C)gamma rays
D)infrared radiation

Question 24

What does a nanometre measure?

A)frequency
B)energy
C)mass
D)length

Question 25

What is the ratio of the light-gathering power of a 10-metre telescope to that of a 1-metre telescope?

A)10 to 1
B)1 to 10
C)100 to 1
D)1 to 100

Question 26

Far-infrared telescopes have to be cooled,but visible-light telescopes do not.Why not?

A)Far-infrared radiation is absorbed by the Earth's atmosphere.
B)Visible-light telescopes detect light from cool objects.
C)Far-infrared telescopes can only work in space.
D)Telescopes are not hot enough to emit visible light.

Question 27

Which of the following types of electromagnetic radiation has the smallest frequency?

A)X-rays
B)visible light
C)radio waves
D)infrared radiation

Question 28

Suppose that you wanted to know how bright a star was at several different wavelengths of light.What kind of instrument would you use?

A)a spectrograph
B)a seismograph
C)a photograph
D)a chromatic aberrator

Question 29

The pupil of the human eye is approximately 0.8 centimetres in diameter when adapted to the dark.What is the ratio of the light-gathering power of a 1.6 metre telescope to that of the human eye?

A)2 : 1
B)20 : 1
C)400 : 1
D)40,000 : 1

Question 30

How do photons of blue light differ from photons of red light?

A)Blue light photons have more energy than photons of red light.
B)Blue light photons have a lower frequency than photons of red light.
C)Blue light photons have a longer wavelength than photons of red light.
D)Blue light photons travel faster than photons of red light.

Question 31

Which of the following types of electromagnetic radiation is absorbed by water low in the Earth's atmosphere but can be detected by telescopes on mountaintops or carried by aircraft?

A)infrared radiation
B)ultraviolet radiation
C)radio wave radiation
D)X-ray radiation

Question 32

How is the objective of most radio telescopes similar to the objective of a reflecting optical telescope?

A)They are both bowl-shaped (concave).
B)They are both hill-shaped (convex).
C)They are typically the same size.
D)They are both made of metal.

Question 33

What does the word "radiation" mean when used by scientists?

A)invisible forms of light such as X-rays and radio waves
B)the light emitted by black holes and protostars
C)high-energy particles from nuclear reactors
D)anything that spreads out from a central source

Question 34

Which property of a telescope determines its light-gathering power?

A)the focal length of the objective
B)the focal length of the eyepiece
C)the diameter of the objective
D)the length of the telescope tube

Question 35

Space telescope A has a diameter of 2.4 metres;space telescope B has a diameter of 6.5 metres.If they take pictures with the same wavelength of light,which telescope will be better able to make separate images of two stars close together on the sky?

A)telescope A
B)telescope B
C)Neither one; if they work at the same wavelength, they will give the same results.
D)Neither one; even in space, telescopes cannot separate objects that are near each other.

Question 36

Which of the following types of electromagnetic radiation has the lowest energy per photon?

A)X-rays
B)ultraviolet light
C)gamma rays
D)infrared radiation

Question 37

What can be done to improve the resolving power of ground-based optical telescopes?

A)Use them at longer wavelengths.
B)Equip them with an adaptive optics system.
C)Change them from reflectors to refractors.
D)Increase their focal length.

Question 38

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?

A)blue light
B)red light
C)both should be the same
D)the amount of detail depends on the distance to the object

Question 39

What is "false" about false-colour images?

A)They are images created by computer simulations.
B)The colours do not represent the colours humans can see.
C)The colours are exaggerated for visual effect.
D)They are images created by artists, not astronomers.

Question 40

What happens to a telescope's light-gathering power and resolving power when you increase its diameter?

A)Its light-gathering power and resolving power both increase.
B)Its light-gathering power increases and its resolving power decreases.
C)Its light-gathering power decreases and its resolving power increases.
D)Its light-gathering power and resolving power both decrease.

Question 41

What type of telescope has a lens as its objective and contains no mirrors?

A)refracting
B)reflecting
C)deflecting
D)compound

Question 42

Which of the following best explains the concept of atmospheric windows?

A)Holes in the Earth's atmosphere allow ultraviolet radiation to reach the North and South poles.
B)X-ray radiation from space can see through the atmosphere to observe activities on the ground.
C)Only certain wavelengths of electromagnetic radiation from space reach the Earth's surface.
D)The Earth's atmosphere can be "closed" or "open" to electromagnetic radiation, depending on the weather.

Question 43

What is the main reason for positioning many radio telescopes across a large area and combining the signals?

A)to provide a backup system if one or more of the telescopes go down
B)to produce higher resolution images
C)to prevent interference between signals from the separate telescopes
D)to compensate for the motion of objects in the sky as a result of the Earth's rotation

Question 44

How is the resolving power of a telescope defined?

A)It is a measure of the minimum angular separation that can be seen with the telescope.
B)It is a measure of the amount of light that the telescope can gather in one second.
C)It is the separation between the objective and the image.
D)It is a measure of how blurry objects appear in the telescope.

Question 45

Which form of electromagnetic radiation travels fastest?

A)gamma rays
B)radio waves
C)all electromagnetic radiation travels at the same speed
D)the speed of radiation depends on the brightness of the source

Question 46

What type of telescope is a radio telescope?

A)reflecting
B)refracting
C)deflecting
D)retracting

Question 47

When does chromatic aberration occur in a telescope?

A)when different colours of light do not focus at the same point in a reflecting telescope
B)when different colours of light do not focus at the same point in a refracting telescope
C)when light of different wavelengths gets absorbed by the mirror in a reflecting telescope
D)when light of different wavelengths gets absorbed by the lens in a refracting telescope

Question 48

What is the relationship between colour and wavelength for light?

A)Wavelength increases from blue light to red light.
B)Wavelength decreases from blue light to red light.
C)All colours of light have the same wavelength.
D)Wavelength depends on intensity, not colour.

Question 49

What is a similarity between radio and optical telescopes?

A)Both are usually located on mountain tops.
B)Both can observe from the Earth's surface.
C)Both are usually made as refracting telescopes.
D)Both can detect radiation with charge-coupled devices.

Question 50

Which of the following could you use to study black holes?

A)a gamma-ray telescope on a mountaintop
B)an infrared telescope at sea level on Earth
C)a radio telescope in space
D)an X-ray telescope in space

Question 51

Which of the following sequences of electromagnetic radiation shows the order of increasing energy correctly?

A)gamma rays, X-rays, infrared, radio
B)visible, ultraviolet, X-rays, gamma rays
C)visible, microwave, radio, infrared
D)infrared, visible, radio, X-rays

Question 52

What is the main reason for building large optical telescopes?

A)It's the best way to see through clouds and other light-absorbers in the atmosphere.
B)It's the best way to collect as much light as possible from faint objects.
C)It's the best way to nullify the blurring effects of the Earth's atmosphere and thus produce higher resolution images.
D)It's the best way to magnify objects and make them brighter.

Question 53

Why can't a telescope image be magnified to show any level of detail?

A)diffraction limits the amount of detail that is visible
B)telescopes only view a small region of the sky
C)magnification depends on focal length
D)resolving power depends on wavelength

Question 54

What is the light-gathering power of a telescope directly proportional to?

A)the diameter of the primary mirror or lens
B)the focal length of the primary mirror or lens
C)the length of the telescope tube
D)the diameter of the eyepiece

Question 55

What type of primary is found in a reflecting telescope?

A)prism
B)mirror
C)lens
D)diffraction grating

Question 56

What statement below best describes the refraction of light?

A)the absorption of light as it travels though a dense, transparent material
B)the spreading out of white light according to wavelength
C)the change in direction of a light ray as it passes to a medium of different optical density
D)the change in direction of a ray of light as it reflects off a surface

Question 57

What is the outstanding construction feature of the largest single-dish radio telescope?

A)It is suspended on cables in a valley.
B)It is buried deep in a mine underground.
C)It is orbiting in space.
D)It is suspended from balloons in the upper atmosphere.

Question 58

You point your backyard reflecting telescope at the star Vega.Where does Vega's light go?

A)From the primary mirror, to the secondary mirror, to the eyepiece.
B)From the primary mirror to the eyepiece.
C)Through the primary lens, to the secondary mirror, to the eyepiece.
D)Through the primary lens, through the secondary lens, to the eyepiece.

Question 59

In which way is a photon of blue light identical to a photon of red light?

A)energy
B)speed
C)wavelength
D)frequency

Question 60

Which of the following has the most light-gathering power?

A)A telescope of 5 centimetres diameter and focal length of 50 centimetres.
B)A telescope of 6 centimetres diameter and focal length of 100 centimetres.
C)A telescope of 2 centimetres diameter and focal length of 100 centimetres.
D)A telescope of 3 centimetres diameter and focal length of 75 centimetres.

Question 61

The ____________________ is a measure of the finest detail that can be seen in an image.

Question 62

The ____________________ is a measure of the clarity of the atmosphere .

Question 63

The ____________________ is a measure of how many times larger the angular size of an object appears through a telescope.

Question 64

What is the most important reason for putting an optical telescope in space?

A)An optical telescope in space observes radiation that does not pass through the Earth's atmosphere.
B)A telescope in space is closer to the objects it observes.
C)Telescopes in space are not subject to the blurring effects of the Earth's atmosphere.
D)An optical telescope in space can be made much larger than one on the ground.

Question 65

The diagram below illustrates the layout and light path of a reflecting telescope of the ____________________ design.

Question 66

The sidereal drive on a telescope mounting must turn the telescope eastward about the polar axis.

Question 67

X-rays easily penetrate the Earth's atmosphere and reach the ground from space.

Question 68

A(n)____________________ telescope has an objective that is a lens.

Question 69

Refracting telescopes suffer from ____________________ aberration.

Question 70

Light can behave as a particle or as a wave.

Question 71

The ____________________ of a telescope is determined by the size of the objective.

Question 72

The Earth's atmosphere blocks most forms of electromagnetic radiation from entering,except for ____________________ and ____________________.

Question 73

The main lens or mirror of a telescope is called the ____________________.

Question 74

The amount of energy a photon carries depends on its wavelength.

Question 75

Reflecting telescopes are no longer popular with astronomers because they are expensive and suffer from chromatic aberration.

Question 76

The process of combining signals from separate telescopes to improve resolution is called ____________________.

Question 77

What is Very Long Baseline Interferometry (VLBI)?

A)a method to observe the largest possible areas of the sky in radio waves
B)a method to observe the largest wavelength optical light
C)linking optical telescopes in different hemispheres to observe the whole sky
D)linking radio telescopes together electronically to provide very high resolution

Question 78

A(n)____________________ uses a mirror as its objective.

Question 79

A(n)____________________ is used to measure the brightness and colour of stars.

Question 80

The largest optical telescope ever constructed was a refracting telescope.