Deck 5: Light and Telescopes

Question 1

____ has (have) wavelengths that are shorter than visible light.

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

Answer 1

I, II, & IV

Question 2

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 above.

Answer 2

westward about the polar axis.

Question 3

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.

Answer 3

is used to improve the resolving power.

Question 4

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 5

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 above.
E) none of the above.

Question 6

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 above.

Question 7

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.

Question 8

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 9

Radio telescopes are important in astronomy because

A) they can detect cool hydrogen.
B) they have high magnification.
C) the can detect interstellar dust clouds.
D) they are very inexpensive to build on tops of mountains.
E) they don't need to be as large as optical telescopes to achieve the same resolving power.

Question 10

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 11

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.

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 above

Question 13

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

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

Question 14

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 15

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 16

____ has (have) wavelengths that are longer than visible light.

A) Gamma rays
B) Ultraviolet light
C) Infrared radiation
D) X-rays
E) a, b and d above

Question 17

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 18

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 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

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.

Question 21

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 22

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 23

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 24

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 25

____ 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 26

Which of the following features 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) tength of the telescope tube
E) none of the above

Question 27

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 28

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 29

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 30

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 above.

Question 31

Increasing the diameter of a telescope

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

Question 32

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 33

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 34

____ 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 35

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 36

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 37

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 38

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 39

The objective of most radio telescopes is similar to the objective 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 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

In a reflecting telescope the objective is a ____.

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

Question 42

Violet light has a wavelength of approximately ____.

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

Question 43

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 44

A telescope whose objective is a lens and contains no mirrors is a(n) ____ telescope.

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

Question 45

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

A) a small-diameter objective reflecting telescope.
B) a small-diameter objective refracting telescope.
C) a large-diameter objective refracting telescope.
D) a large-diameter objective reflecting telescope.
E) the Hubble Space Telescope.

Question 46

CCD stands for a

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

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

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 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 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 52

There are ____ nanometers in one meter.

A) 1*10³
B) 1*^-3
C) 1*10⁹
D) 1*10^-9
E) 400

Question 53

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 54

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 55

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

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

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

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 58

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 59

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 60

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 61

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

Question 62

Refracting telescopes suffer from ____________________ aberration.

Question 63

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 above.

Question 64

A convex lens is located at "B" and a light sources between "D" and "C". Where will an image of the light source form in the sketch?

A) A
B) B
C) C
D) D

Question 65

Which blurs our Earth-based view of celestial objects?

A) the sun
B) the moon
C) Earth's atmosphere

Question 66

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 67

The Hubble Space Telescope objective mirror is not affected by

A) bad seeing.
B) chromatic aberration.
C) diffraction.
D) Answers b and c
E) Answers a and b

Question 68

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

A) reflection
B) refraction
C) diffraction

Question 69

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

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

Question 70

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

Question 71

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

Question 72

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

Question 73

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

Question 74

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 though 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 which is of different optical density.
D) Light rays are focused to form an image after they reflect off the lens.

Question 75

Which of the items below is electromagnetic radiation?

A) gamma rays
B) X-rays
C) visible light
D) radio
E) all of the above

Question 76

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

A) X-rays
B) Radio waves
C) Visible light
D) Answers a and b
E) Answers b and c

Question 77

A wave on a lake is found to have a wavelength of 2 m and a frequency of 0.3 Hz. What is the speed of this wave?

Question 78

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

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

Question 79

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

Question 80

Which of the waves below has the shortest wavelength?

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