Deck 5: Light and Telescopes

Question 1

Long wavelength visible light

A) will have a greater energy than short wavelength visible light.
B) will have a speed that is faster than short wavelength light.
C) has a higher frequency than short wavelength visible light.
D) will appear blue in color to the average human eye.
E) will appear red in color to the average human eye.

Answer 1

E

Question 2

A telescope that suffers from chromatic aberration and has a low light-gathering power is most likely

A) a small-diameter reflecting telescope.
B) a small-diameter refracting telescope.
C) a large-diameter refracting telescope.
D) a large-diameter reflecting telescope.
E) an infrared telescope.

Answer 2

B

Question 3

The Very Long Baseline Array (VLBA)

A) is the highest resolution optical telescope ever built.
B) is located in Arecibo, Puerto Rico.
C) is a matched pair of 8 m telescopes, one of which is in Chile and the other in Hawaii.
D) is an air-borne infrared telescope.
E) is a set of radio telescopes linked together electronically to provide very high resolution.

Answer 3

E

Question 4

A new generation of ground-based telescopes is currently being built that overcomes the limitations of the older large telescopes. Some of these new telescopes

A) use segmented mirrors.
B) use mirrors that are very thin.
C) use active optics to control the shape of the mirror.
D) All of the other choices are correct.
E) None of the other choices are correct.

Question 5

Radio telescopes have poor resolving power because

A) their diameters are so large.
B) the energy they receive is not electromagnetic radiation.
C) radio waves have long wavelengths.
D) their diameters are so large and the energy they receive is not electromagnetic radiation.
E) None of the other choices are correct.

Question 6

The ____ 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
E) spherical aberration

Question 7

A __________ is a piece of glass with many small parallel lines etched on its surface to produce a spectrum.

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

Question 8

The technique of connecting multiple telescopes together to combine the images from each telescope is known as

A) aberration.
B) resolving power.
C) active optics.
D) adaptive optics.
E) interferometry.

Question 9

The sidereal drive of a telescope mounting must turn the telescope

A) southward about the polar axis.
B) eastward about the polar axis.
C) westward about the polar axis.
D) northward about the polar axis.
E) None of the other choices are correct.

Question 10

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

A) 400 nm
B) 4000 nm
C) 7000 nm
D) 700 nm
E) 3 × 10⁸ m

Question 11

Far infrared astronomy must be done from high-flying aircraft because

A) far infrared radiation is absorbed low in Earth's atmosphere.
B) far infrared photons are quite energetic.
C) far infrared telescopes are not very heavy.
D) far infrared sources are very bright.
E) None of the other choices are correct.

Question 12

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

A) an optical telescope
B) the VLBA telescope
C) an X-ray telescope
D) a radio telescope
E) None of the other choices are correct.

Question 13

Ultraviolet radiation from a star

A) will not penetrate Earth's atmosphere and reach the ground.
B) has a wavelength that is longer than the visible light emitted by the star.
C) has a wavelength that is shorter than the X-rays emitted by the star.
D) will not penetrate Earth's atmosphere and reach the ground and has a wavelength that is longer than the visible light emitted by the star.
E) has a wavelength that is longer than the visible light emitted by the star and has a wavelength that is shorter than the X-rays emitted by the star.

Question 14

Photons of blue light

A) have a greater energy than photons of red light.
B) have a greater energy than photons of ultraviolet light.
C) have a lower frequency than photons of red light.
D) have a longer wavelength than photons of red light.
E) travel at a greater speed than photons of red light.

Question 15

The energy of a photon

A) is proportional to the wavelength of the light.
B) is inversely proportional to the wavelength of the light.
C) depends only on the speed of the light.
D) depends only on the mass of the photon.
E) depends on both the mass and speed of the photon.

Question 16

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

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

Question 17

____ has (have) wavelengths that are shorter than visible light.
I) Gamma rays
II) Ultraviolet light
III) Infrared radiation
IV) X-rays

A) I & II
B) I & IV
C) II & III
D) II, III, & IV
E) I, II, & IV

Question 18

Interferometry

A) is used to improve the resolving power.
B) decreases the chromatic aberration of a telescope.
C) works only for large X-ray and ultraviolet telescopes.
D) requires that radio telescopes be within a few hundred feet of each other.
E) is none of the above.

Question 19

A ___________ has a few million light-sensitive diodes in an array typically about a half-inch square.

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

Question 20

Astronomers build optical telescopes on tops of mountains because

A) there is less air to dim the light.
B) the seeing is better.
C) CCDs work better with a beautiful mountain view.
D) All of the choices are correct.
E) there is less air to dim the light and the seeing is better.

Question 21

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

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

Question 22

The primary mirrors of most radio telescopes is similar to the primary mirror of a reflecting optical telescope in that

A) they are both concave in shape.
B) they are both convex in shape.
C) they are typically the same size.
D) they are both made of metal.
E) they have nothing in common.

Question 23

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

A) 10 to 1
B) 1 to 10
C) 100 to 1
D) 1 to 100
E) 3.2 to 1

Question 24

Blue light differs from red light in that

A) blue light has a higher energy than red light.
B) blue light has a lower energy than red light.
C) blue light has a shorter wavelength than red light.
D) blue light has a longer wavelength than red light.
E) More than one of the other choices are correct.

Question 25

Increasing the diameter of a telescope
I) increases its light-gathering power.
II) increases its resolving power.
III) increases it magnifying power.
IV) increases its chromatic aberration.

A) I, II, III, & IV
B) I, II, & III
C) I, II, & IV
D) III & IV
E) I & II

Question 26

An achromatic lens

A) is used to correct spherical aberration in reflecting telescopes.
B) is used to correct chromatic aberration in refracting telescopes.
C) is used to correct spherical aberration in refracting telescopes.
D) is used to correct chromatic aberration in reflecting telescopes.
E) contains two mirrors and focuses the light back through the primary mirror.

Question 27

The resolving power for light of 550 nm of an optical telescope with a diameter of 232 cm is

A) 0.05 arc seconds.
B) 232 arc seconds.
C) 2.32 arc seconds.
D) 5 arc seconds.
E) 11.6 arc seconds.

Question 28

_________ is absorbed by water in Earth's atmosphere and requires that telescopes for observing at these wavelengths be placed on mountain tops or in space.

A) Infrared radiation
B) Ultraviolet radiation
C) Radio wave radiation
D) X-ray radiation
E) Visible light

Question 29

The optical shape of segmented mirrors is controlled by computer-driven thrusters under the mirrors in what is called

A) an achromatic lens.
B) active optics.
C) a Schmidt-Cassegrain design.
D) a Newtonian design.
E) interferometry.

Question 30

___________ is absorbed by ozone in Earth's atmosphere that is located between 20 km and 40 km above Earth's surface. Therefore, telescopes to observe this radiation must be placed in space.

A) Infrared radiation
B) Ultraviolet radiation
C) Radio wave radiation
D) X-ray radiation
E) Visible light

Question 31

What is the frequency of the shortest wavelength light that can be detected by the average human eye?

A) 0.0025 Hz
B) 7.5 × 10¹⁴ Hz
C) 3.0 × 10⁸ m/s
D) 700 nm
E) 400 nm

Question 32

Which of the following features of a telescope determines its light-gathering power?

A) the focal length of the primary lens
B) the focal length of the eyepiece
C) the diameter of the primary lens
D) length of the telescope tube
E) None of the other choices are correct.

Question 33

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

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

Question 34

A nanometer is

A) a unit of frequency.
B) a unit of energy.
C) a unit of mass.
D) a unit of length.
E) a unit of resolving power.

Question 35

What is the wavelength of light that has a frequency of 3 MHz?

A) 9 × 10¹⁴ Hz
B) 1 × 10¹⁴ m
C) 9 × 10¹⁴ m
D) 100 m
E) 0.01 m

Question 36

The pupil of the human eye is approximately 0.8 cm in diameter when adapted to the dark. The ratio of the light-gathering power of a 1.6-m telescope to that of the human eye is ____.

A) 2
B) 4
C) 20
D) 400
E) 40,000

Question 37

What is the magnification of a telescope and eyepiece if the telescope objective has a focal length of 200 cm and the eyepiece has a focal length of 2.0 cm?

A) 400 times
B) 4000 times
C) 100 times
D) 1000 times
E) 40 times

Question 38

In which way does a photon of blue light NOT differ from a photon of red light?

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

Question 39

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

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

Question 40

What is the relationship between color and wavelength for light?

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

Question 41

Violet light has a wavelength of approximately _______.

A) 400 nm
B) 4000 nm
C) 7000 nm
D) 700 nm
E) 3 × 10⁸ m

Question 42

There are _______ nanometers in one meter.

A) 1 × 10³
B) 1 × 10 ^{− 3}
C) 1 × 10⁹
D) 1 × 10 ^{− 9}
E) 400

Question 43

What is the ratio of the light-gathering power of a 5-m telescope to that of a 0.5-m telescope?

A) 10
B) 0.1
C) 0.01
D) 100
E) 25

Question 44

CCD stands for a

A) photometer.
B) charge-coupled device.
C) spectrograph.
D) core collapse device.
E) grating.

Question 45

The technique called _______ uses a high-speed computer to monitor atmospheric distortion and adjust the optics of a telescope to partially compensate for the seeing.

A) photometry
B) chromatic aberration
C) active optics
D) spherical aberration
E) adaptive optics

Question 46

What is the wavelength of the shortest wavelength light visible to the human eye?

A) 400 nm
B) 4000 nm
C) 7000 nm
D) 700 nm
E) 3 × 10⁸ m

Question 47

Chromatic aberration occurs in a ________ telescope when __________.

A) reflecting; different colors of light do not focus at the same point
B) refracting; different colors of light do not focus at the same point
C) reflecting; light of different wavelengths get absorbed by the mirror
D) refracting; light of different wavelengths get absorbed by the lens

Question 48

What statement below best describes the refraction of light?

A) The absorption of light as it travels through 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 49

The resolving power of a telescope is

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

Question 50

A _______ is used to produce and analyze a spectrum.

A) photo
B) spectrograph
C) photometer
D) charge-coupled device

Question 51

The largest single-dish radio telescope is

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

Question 52

In a reflecting telescope the primary is a _______.

A) prism
B) mirror
C) lens
D) diffraction grating
E) photographic plate

Question 53

A telescope whose primary is a lens and contains no mirrors is a(n) _______ telescope.

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

Question 54

Which of the following sequences of electromagnetic radiation is correct in order of increasing energy?

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

Question 55

Observations of radio waves from astronomical objects suffer from poorer resolution than visible observations with the same size dish (or mirror) because

A) the signals are so weak in the radio region.
B) the wavelength of radio waves is much longer than the wavelengths of visible light.
C) radio telescopes are generally much smaller in diameter than optical telescopes.
D) it is very difficult to detect radio waves.
E) radio telescopes don't use solid mirrors.

Question 56

The light-gathering power of a telescope is directly proportional to

A) the diameter of the primary mirror or lens.
B) the focal length of the primary mirror or lens.
C) the ratio of the focal lengths of its primary mirror or lens and its eyepiece.
D) the length of the telescope tube.
E) the diameter of the eyepiece.

Question 57

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

A) to observe more objects in a shorter amount of time.
B) provide a backup system if one or more of the telescopes go down.
C) to produce higher resolution images.
D) to avoid interference between signals from the separate telescopes.
E) to account for the motion of objects in the sky as a result of the Earth's rotation.

Question 58

Which has the larger light-gathering power?

A) a telescope of 5 cm diameter and focal length of 50 cm
B) a telescope of 6 cm diameter and focal length of 100 cm
C) a telescope of 2 cm diameter and focal length of 100 cm
D) a telescope of 3 cm diameter and focal length of 75 cm
E) both b and c since they have the same focal length.

Question 59

Radio telescopes which use dishes to gather radio waves are _______ telescopes.

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

Question 60

The main reason for building large optical telescopes on Earth's surface is

A) that there is a lot of money in science that needs to get spent.
B) to collect as much light as possible from faint objects.
C) to nullify the blurring effects of the Earth's atmosphere and thus produce higher resolution images.
D) to bring astronomical objects closer to make them brighter.
E) that the warm temperatures of the Earth's surface allow for easier telescope operation.

Question 61

A ______________ is an array of electromagnetic radiation and a ___________ is an instrument that spreads light according to color.

A) prism, mirror
B) lens, grating
C) rainbow, prism
D) spectrum, spectrograph

Question 62

Reflecting telescope objectives here on Earth do not have a problem with

A) "seeing".
B) diffraction.
C) color fringes on the image.
D) All of the other choices are correct.

Question 63

Infrared space telescopes must have their mirror cooled to very low temperatures because otherwise it would thermally emit too much _______ itself.

A) infrared radiation
B) radio waves
C) X-rays
D) gamma rays
E) all of the above

Question 64

The Hubble Space Telescope objective mirror is not affected by

A) bad seeing.
B) chromatic aberration.
C) diffraction.
D) chromatic aberration and diffraction.
E) bad seeing and chromatic aberration.

Question 65

Assume you are not near any X-ray machines. If your eyes could only see in X-rays, what color would best describe your view of your surroundings?

A) white
B) red
C) violet
D) black

Question 66

Which blurs our Earth-based view of celestial objects?

A) the Sun
B) the Moon
C) Earth's atmosphere

Question 67

__________ in Earth's atmosphere absorbs most microwave and infrared radiation coming from outside Earth's atmosphere.

A) Ozone
B) Water vapor
C) Methane
D) Carbon dioxide

Question 68

If your eyes could only see in gamma rays, what color would best describe your view of your surroundings?

A) white
B) red
C) violet
D) black

Question 69

__________ in Earth's atmosphere absorbs most ultraviolet radiation coming from the Sun.

A) Methane
B) Three bound oxygen atoms
C) Water vapor
D) Carbon dioxide

Question 70

A larger-primary lens shows ____________ a smaller-primary lens.

A) more detail than
B) less detail than
C) the same amount of detail as

Question 71

In modern astronomy, an interferometer

A) is the highest resolution optical telescope ever built.
B) is located in Arecibo, Puerto Rico.
C) is a set of optical telescopes linked together to provide very high resolution.
D) is a set of radio telescopes linked together to provide very high resolution.
E) is either a set of optical telescopes linked together to provide very high resolution or is a set of radio telescopes linked together to provide very high resolution.

Question 72

What statement below best describes the behavior of light encountering the objective lens of a refracting telescope?

A) All light is absorbed as it travels through a dense, transparent material.
B) White light from astronomical objects is emitted by the lens.
C) Light rays are focused to form an image after they pass through the lens.
D) Light rays are focused to form an image after they reflect off the lens.

Question 73

On the Moon, no air is present. As such, which of the following waves cannot be detected.

A) optical
B) infrared
C) radio
D) sound

Question 74

Which of the items below is electromagnetic radiation?

A) gamma rays
B) X-rays
C) visible light
D) radio
E) All of the other choices are correct.

Question 75

If you focused a store-bought telescope at a tree down the street on a clear day, the tree would be viewed as ______________ and _____________.

A) right side up, larger
B) upside down, larger
C) right side up, smaller
D) upside down, smaller

Question 76

Microwaves have ________ wavelengths and ________ energies compared to the visual band.

A) shorter, higher
B) longer, lower
C) shorter, lower
D) longer, higher

Question 77

_______ penetrate(s) the Earth's atmosphere to reach its surface.

A) X-rays
B) Radio waves
C) Visible light
D) X-rays and radio waves
E) Radio waves and visible light

Question 78

An ordinary glass lens forms an image by ____________ of light.

A) reflection
B) refraction
C) diffraction

Question 79

Which of the waves below has the shortest wavelength?

A) gamma rays
B) X-rays
C) visible light
D) infrared
E) radio

Question 80

Compared to a smaller-objective lens, a larger-objective lens makes a star's image

A) brighter.
B) dimmer.
C) no effect.