Exploring the Cosmos - Mapping the Universe
1. Which of the following statements correctly describes the wavelength of an electromagnetic wave?
The wavelength is the distance travelled by the wave in 1 second.
The wavelength is the distance between a trough and a peak.
The wavelength is the distance travelled by the wave in a short time.
The wavelength is the distance between two consecutive peaks.
2. Why does a light ray bend when it crosses the boundary between two different media at an oblique angle?
Because it interferes with the surface.
Because the speed of light changes.
Because the amplitude is reduced.
Because the frequency increases.
3. A Newtonian telescope has
a correction plate
a diverging secondary mirror
a flat secondary mirror
just the primary mirror
4. As light passes from one medium to another, its direction of travel changes. What is the name of this effect?
Interference
Refraction
Diffraction
Dispersion
5. Diffraction gratings are used to
break up light into a spectrum.
detect infrared radiation.
reduce diffraction of telescopes.
increase the resolution of telescopes.
6. The speed of light in glass is
reduced by approximately 60%
the same as in vacuum
increased by approximately 50%
reduced by approximately 1%
7. Diffraction gratings are used for
detecting microwave radiation.
reducing the diffraction of telescopes.
analysing the light spectrum.
increasing the angular resolution of telescopes.
8. Which of the following parameters is the same for all electromagnetic waves propagating in a vacuum?
Wavelength
Amplitude
Colour
Speed
9. Which of the following parameters is the same for all electromagnetic waves propagating in a vacuum?
Amplitude
Speed
Colour
Wavelength
10. Why does a light ray bend when it crosses the boundary between two different media at an oblique angle?
Because it interferes with the surface.
Because the frequency increases.
Because the speed of light changes.
Because the amplitude is reduced.
11. A Newtonian telescope has
a correction plate.
a flat secondary mirror.
just the primary mirror.
a diverging secondary mirror.
12. The Hubble telescope was placed in space in order
to be close to the stars.
to not be limited by the Earth’s atmosphere.
to not be limited by the Earth’s horizon.
to improve the magnification.
13. An electromagnetic wave with a wavelength of 600 nm is
infrared radiation.
microwave radiation.
ultraviolet radiation.
visible radiation.
14. Which of the following uses a grazing incidence telescope?
International Space Observatory.
International Ultraviolet Explorer.
International Space Station.
Chandra X-ray satellite.
15. The angle through which a ray of light is bent by a glass prism depends on the
brightness of the light.
wavelength of the light.
reflectivity of the prism.
photoelectric effect.
16. The focal length of an ideal mirror depends on
photoelectric effect.
brightness of the light.
reflectivity of the prism.
wavelength of the light.
17. Light can be described as having a “dual†nature. What does this mean?
Light behaves like a wave and like a particle.
If light moves in one direction, then it moves in the opposite direction also.
Light goes slow and fast.
Light can be expressed as brightness and colour.
18. What is the angular size of the Moon?
0.5 degrees
5 degrees
0.5 arcseconds
0.5 arcminutes
19. Which of the following space-based telescopes detected water in the Orion nebula?
The International Ultraviolet Explorer (IUE)
The International Space Observatory (ISO)
Hubble
Chandra
20. If the width of the objective of a telescope is doubled, what happens to its light gathering power?
The light gathering power increased by a factor of four.
The light gathering power remains the same.
The light gathering power is decreased by a factor of four.
The light gathering power is increased by a factor of two.
21. For a telescope the objective focal length is 80 cm and the eyepiece focal length is 2 cm, what is the magnification?
160
78
less than 1
40
22. To detect dim objects a telescope needs
high magnification.
large diameter.
a long tube.
high resolution.
23. A Charge Coupled Device is used in telescopes to
reduce the effect of segmentation of mirrors.
detect light.
improve light gathering.
compensate for sagging of the mirror.
24. Long Baseline Interferometry is a technique often used in radio astronomy to
reduce the effect of light pollution in urban skies.
image neutrinos.
remove the effect of Cerenkov radiation.
improve the resolution of objects.
25. Karl Jansky was the pioneer of
optical astronomy
UV astronomy.
radio astronomy.
infra-red astronomy.
26. The LIGO gravitational wave detectors
are currently under construction.
are bar detectors.
have arm lengths of 4 km.
have arm lengths of 600 m.
27. Cerenkov radiation is given off when
a particle is travelling faster than the speed of light in a medium
a particle is travelling slower than the speed of light in a medium
an electron is ionised from an atom
an electron recombines with an ionised atom
28. Why is the colour of the sun during sunset red?
The refraction of light is different. Blue light is more strongly refracted.
The diffraction of light is different. Blue light is more strongly diffracted.
The scattering of blue light is stronger than red light.
The sun changes its colour in 24 h from blue to red and back to blue.
29. Which of the following processes is responsible for the absorption of Infra-Red radiation?
Splitting of the atomic nuclei.
Infra-Red radiation is not absorbed.
Excitation of vibrational modes of molecules.
Breaking of the chemical bonds.
30. The ISO satellite is sensitive to
IR.
UV.
Gamma rays.
X-rays.
31. The objective of a telescope is
the object under observation.
the reason why that telescope has been buil
the adaptor between the telescope and the human eye.
the part of it which first converges the light.
32. As light passes from one medium to another, its direction of travel changes. What is the name of this effect?
Dispersion
Interference
Refraction
Diffraction
33. How does an infrared telescope make detections?
By monitoring the number of electrons released by incident photons.
By directly detecting the number of incident photons.
By detecting oscillating electric signals generated by incident photons.
By monitoring changes in temperature caused by incident photons.
34. Which of the following processes is responsible for absorption of infrared radiation by the atmosphere?
Conduction in an upper part of the atmosphere.
The excitation of the vibrational modes of water vapour molecules.
The breaking of chemical bonds in ozone.
Interaction of the radiation with the nuclei of atoms in the atmosphere.
35. The twinkling of the stars is due to
diffusion.
refraction.
scattering.
absorption.
36. A Charge Coupled Device is used in telescopes to
detect light.
improve light gathering.
reduce the effect of segmentation of mirrors.
compensate for sagging of the mirror.
37. The Spitzer satellite uses
a Schmidt-Cassegrain design
a grazing incidence mirror
a Cassegrain design
a prime focus arrangement
38. The ISO satellite is sensitive to
X-rays.
IR.
UV.
Gamma rays.
39. Why are neutrinos so hard to detect in astronomical observatories?
There are no astronomical sources of neutrinos.
The neutrinos decay before reaching the Earth.
Neutrinos are absorbed in the upper atmosphere.
The neutrinos interact only weakly.
40. The Chandra Observatory is an observatory for
Radio astronomy.
X-Ray astronomy.
Neutrino astronomy.
Infra-red astronomy.
41. Why are astronomers interested in different parts of the spectrum?
Different parts of the spectrum contain different information.
At some locations at the sky certain detectors do not work.
The results would otherwise interfere destructively.
The different colours are nice.
42. An electromagnetic wave having a wavelength of 550 nm is:
visible radiation.
ultra-violet radiation.
infrared radiation.
gamma radiation.
43. Karl Jansky was the pioneer of
optical astronomy.
radio astronomy.
UV astronomy.
infra-red astronomy.
44. A grazing incidence mirror is used to focus
x-rays.
gravitational waves.
gamma rays.
visible light.
45. Modern observatories are placed on mountains
to be able to observe X-rays
to reduce the amount of turbulent atmosphere
because it is cheaper to build them on mountains
to get closer to the stars
46. The Super Kamiokande Neutrino observatory
is a future planned detector in Japan
is located in the Mediterranean sea
is located underground in the USA
is located underground in Japan
47. Cerenkov radiation is given off when
an electron recombines with an ionised atom
a particle is travelling faster than the speed of light in a medium
an electron is ionised from an atom
a particle is travelling slower than the speed of light in a medium
48. The typical sensitivity of interferometric gravitational wave detectors is of the order
1 millimeter
1 attometer
1 micrometer
1 nanometer
49. The Compton Gamma Ray Observatory
has instruments to look at multiple energy bands
has imaging CCDis
has grazing incidence mirrors to focus the high energy gamma rays
uses a large tank of water as a scintillation detector
50. Radio telescopes
do not require a very smooth surface.
require a very smooth surface.
need to be cooled.
operate only at night.
51. LIGO is an acronym for:
Light Ingoing Ground Observations.
Laser Incoming Ground Observation.
Laser Interferometric Gravitational-wave Observatory.
Light Incident Gravitational Observation.
52. Long Baseline Interferometry is a technique often used in radio astronomy to
remove the effect of Cerenkov radiation.
improve the resolution of objects.
reduce the effect of light pollution in urban skies.
image neutrinos.
53. Chromatic aberration can occur in a telescope because
the telescope is not stable.
the atmosphere is not stable.
light of different wavelengths are reflected to different positions.
light of different wavelengths are focussed to different positions.
54. The speed of light in a vacuum is approximately
30 thousand metres per second.
300 million metres per second.
300 thousand metres per second.
30 million metres per second.
55. The term 'refraction' is used to describe when light
changes frequency when transmitting through different media.
waves add together to produce brighter light.
changes direction when transmitting through different media.
bends around the edges of objects.
56. For an astronomical source, the focal length of a mirror is
the diameter of the mirror.
the thickness of the mirror.
the distance from the mirror to an object.
the distance from the mirror to the focal point.
57. Light can be described as having a "dual" nature. What does this mean?
It can go fast and slow.
It behaves like a wave and a particle.
It has brightness and wavelength.
It travels in two directions at the same time.
58. A Newtonian telescope is
a Cassegrain telescope.
a refracting telescope.
a prime focus telescope.
a reflecting telescope.
59. Astronomers hope to discover gravitational waves by
placing radio telescopes in space.
detecting high-energy gamma rays.
using laser interferometers.
using highly-sensitive CCD sensors.
60. During the day the sky appears blue because
the scattering of blue light is stronger than red light.
blue light is refracted less than red light.
the atmosphere reflects more red light from the Sun during the day.
the Sun changes colour over a period of 24 hours.
61. Atmospheric absorption causes
dimming or extinction of certain wavelengths of light.
the stars to twinkle in appearance.
the scattering of light with large wavelengths.
the light from stars to appear stronger than it should.
62. The resolving power of a radio telescope can be increased by
putting the telescope on a mountain.
making observations during the night.
increasing the diameter of the primary mirror.
decreasing the diameter of the primary mirror.
63. A Schmidt-Cassegrain telescope is one that has?
A corrector plate and a primary mirror only.
Only lenses.
Only mirrors.
A corrector plate, a primary mirror and a secondary mirror.
64. Why are astronomers interested in measuring light at different parts of the electromagnetic spectrum?
Because visible light is hard to detect on Earth.
Stars emit mainly ultraviolet radiation.
Because in vacuum light travels at different speeds at different wavelengths.
Different parts of the spectrum provide different information.
65. What does the frequency of light mean?
How bright the light will be.
The number of times the wave cycle repeats every second.
The distance it will travel in 1 second.
The distance from one maximum to another.
66. The energy of a photon can be expressed by
E=hc.
E=f/λ.
E=hf.
E=cλ.
67. What is the purpose of the objective lens in a refracting telescope?
To diffract the incoming light.
To change the speed of the incoming light.
To focus the incoming light.
To interfere the incoming light.
68. If a refracting telescope has an objective lens with a focal length of 300cm and has an eyepiece with a focal length of 3cm, the magnification is?
M = 300.
M = 1/100.
M = 3/300.
M = 100.
69. Active optics is used in modern telescopes to
change the detector sensitivity for measuring different wavelengths.
change the focal length of the primary mirror for different astronomical objects.
change the shape of the primary mirror to correct for atmospheric disturbances.
maximise the light gathering power of the telescope.
70. The Earth’s atmosphere is responsible for which three phenomena in observational astronomy?
Atmospheric refraction, Atmospheric scattering, and Atmospheric absorption.
Wave particle duality, Atmospheric scattering, and Atmospheric absorption.
Atmospheric scattering, Spherical aberration, and Atmospheric refraction.
Atmospheric diffraction, Chromatic aberration, and Atmospheric scattering.
71. For what reason is interferometry used when using multiple telescopes to observe astronomical objects?
To reduce the magnification.
To remove the effect of light pollution.
To increase the resolving power of the detector.
To measure different frequencies of light simultaneously.
72. Gravitational wave detectors aim to measure the radiation emitted by accelerating masses by
using the James Webb Space Telescope.
using multiple radio telescopes around the world.
using long-baseline laser interferometers.
detecting Cherenkov radiation with photomultiplier tubes.
73. Which of the following statements is false?
Red light has a longer wavelength than blue light.
Light is a wave of varying electric and magnetic fields.
Light travels faster in glass than in a vacuum.
Light is both a wave and a particle.
74. A Schmidt-Cassegrain telescope uses which of the following components?
A diffraction grating.
Only mirrors.
Both lenses and mirrors.
Only lenses.
75. If a telescope has an objective with a focal length of 90 cm and an eyepiece with focal length of 3 cm, what is the magnification of the telescope?
60
1/30
270
30
76. What are the three important qualities of a telescope?
Magnification, Diffractive Power, Resolving Power.
Magnification, Diffractive Power, Light Gathering Power.
Magnification, Light Gathering Power, Resolving Power.
Diffractive Power, Light Gathering Power, Resolving Power.
77. What causes the twinkling of stars?
Atmospheric Dispersion.
Impurities in the lens of the telescope or eye.
Atmospheric refraction.
The variation in intensity of light emitted by the star.
78. On a cloudless day, why does the sky look blue?
Because red light is scattered more than blue light.
Because blue light is scattered more than red light.
Because the sky reflects the blue colour of the sea.
Because the red light is absorbed by the atmosphere.
79. Grazing incidence mirrors are used to focus light in what type of telescope?
Optical telescopes.
Infra-red telescopes.
Radio telescopes.
X-Ray telescopes.
80. By what method are radio telescopes able to obtain high-resolution images?
By having a large field of view.
By using laser guide adaptive optics.
By using computer grinding to construct very smooth mirrors.
By using the interference of signals from many radio telescopes.
81. Super-Kamiokande is an experiment designed to detect what?
Gamma rays.
Neutrinos.
Earth-like planets.
Gravitational waves.
82. The James Webb telescope is intended to replace what?
The Infra Red Astronomical Satellite.
The Hubble Space telescope.
The Compton Gamma Ray observatory.
The Chandra observatory.
83. Which of the following is a true statement?
Light is both a wave and a particle.
Light is a wave, but not a particle.
Light is neither a wave nor a particle.
Light is a particle, but not a wave.
84. Which of the following describes waves whose wavelength is approximately 1 mm?
Visible red light.
X-Rays.
Microwaves.
Radio waves.
85. What is the phenomenon where the velocity of light in a medium depends on its wavelength?
Diffraction
Interference
Refraction
Dispersion
86. Newton's telescope was a
prime focus telescope.
Cassegrain telescope.
refracting telescope.
reflecting telescope.
87. Modern telescopes use CCDs to capture the light. What does the acronym CCD stand for?
Charge Coupled Diode.
Count Collecting Device.
Charge Coupled Device.
Charge Collecting Diode.
88. Ultra-Violet (UV) radiation is emitted by objects of temperature around
1 000 000 K
500 K
10,000 K
10 K
89. The Chandra Observatory is an observatory for
X-Ray astronomy.
Radio astronomy.
Neutrino astronomy.
Infra-red astronomy.
90. Why can X-Rays penetrate inside solids?
They are of very small frequency.
They have very small wavelengths.
They are out of phase with ordinary matter.
They are very non-reactive.
91. Why are neutrinos so hard to detect in astronomical observatories?
Neutrinos are absorbed in the upper atmosphere.
There are no astronomical sources of neutrinos.
The neutrinos interact only weakly.
The neutrinos decay before reaching the Earth.
92. Which of the following is NOT a good source of gravitational waves?
Supernova explosions.
Magellanic clouds.
Black Hole binary systems.
Pulsars.
93. A reflective diffraction grating is separating the light colours and creates a spectrum. What happens if the incoming light is changed from blue to red?
The angle between the diffraction orders becomes larger.
Nothing. Diffraction is wavelength-independent.
The red light is transmitted through the grating because only blue light is scattered.
The outcoming light stays blue.
94. Which statement is wrong?
Light has a constant speed in vacuum.
Light travels always with a constant speed.
The energy of photons is just dependent on the frequency.
Light travels with different speeds depending on the material.
95. Why are most of the modern telescopes for visible light reflecting telescopes?
Lenses cannot be used for visible light.
Mirrors are easier to make and to mount.
It is not possible to melt enough glass to fabricate a large lens.
They have no aberration.
96. Why are astronomers interested in different parts of the spectrum?
The results would otherwise interfere destructively.
Different parts of the spectrum contain different information.
At some locations at the sky certain detectors do not work.
The different colours are nice.
97. A Cassegrain telescope may have a focal length of 100 cm. The diameter of the mirror shall be 25 cm. The eyepiece used in this configuration has a focal length of 1 cm and a diameter of 0.5 cm. What magnification is achieved?
It is not possible to calculate the magnification with these parameters.
A magnification of 25.
A magnification of 50.
A magnification of 100.
98. Why is the colour of the sun during sunset red?
The sun changes its colour in 24 h from blue to red and back to blue.
The diffraction of light is different. Blue light is more strongly diffracted.
The scattering of blue light is stronger than red light.
The refraction of light is different. Blue light is more strongly refracted.
99. What is true for an IR detector used in astronomy?
The electrons in the detector need to get some additional energy to be used for detection. Thus, these detectors need to be heated.
Light is absorbed and the temperature increase is measured. Therefore, it is good to cool them.
They are not used. The IR part of the spectrum does not contain any information.
They are based on the photoelectric effect: light kicks out electrons from the material.
100. What is the reason why X-ray telescopes are so much different from telescopes for the visible part of the spectrum?
It is hard to find materials that can be used under X-ray irradiation.
Materials are nearly transparent in the X-ray band. Standard optical configurations cannot be used.
It is too dangerous to observe X-rays from astronomical objects.
Materials used in these telescopes change the colour of the light. It is complicated to compensate this effect.
101. What can be observed with radio astronomy?
Wavelengths that are in the region of cm.
Wavelengths that are shorter than the visible light.
The moon.
Radio broadcast of other civilizations in the universe.
102. Gravitational wave astronomy is called a new window to the universe. Why?
Gravitational waves can be observed with a simple refractive telescope. Therefore, it would be easier to observe astronomical objects.
They need to be observed from space.
Gravitational waves will allow a very high resolution when combining a gravitational wave telescope with a CCD.
Gravitational waves have only a weak interaction with matter. They are carrying information from objects that cannot be observed by studying their emitted electromagnetic radiation.
103. Adaptive optics is a technique that reduces the effect of atmospheric turbulence by
varying the mirror reflectivity.
adjusting the eyepiece position
evacuating the telescope tube.
bending the telescope mirror.
104. The angular size of the Moon is
0.1 degree
5 degrees.
0.5 degree.
50 degrees.
105. Which of the following uses a grazing incidence telescope?
Hubble Space telescope.
Spitzer.
Chandra.
International Ultraviolet Explorer.
106. Modern observatories mostly use
refractive objectives.
observatories at low altitude.
photographic film.
CCD detectors.
107. LIGO is an acronym for:
Laser Incoming Ground Observation.
Laser Interferometric Gravitational-wave Observatory.
Light Ingoing Ground Observations.
Light Incident Gravitational Observation.
108. If the diameter of the objective of a telescope is doubled, what happens to its light gathering power? The light gathering power
is increased by a factor of two.
is increased by a factor of three.
is increased by a factor of four.
remains the same.
109. Which of the following processes is responsible for the absorption of Infra-Red radiation?
Infra-Red radiation is not absorbed.
Excitation of vibrational modes of molecules.
Breaking of the chemical bonds.
Splitting of the atomic nuclei.
110. Long Baseline Interferometry is a technique often used in radio astronomy to
image neutrinos.
reduce the effect of light pollution in urban skies.
improve the resolution of objects.
remove the effect of Cerenkov radiation.
111. An electromagnetic wave having a wavelength of 550 nm is:
gamma radiation.
ultra-violet radiation.
infrared radiation.
visible radiation.
112. In a diffraction grating the angle between the zero order (white fringe) and first order (coloured fringe) depends on the
brightness of the light.
intensity of the light.
speed of the light.
wavelength of the light.
113. A Cassegrain telescope
is a common optical design used at modern observatories.
has a short focal length.
is not a widely used optical design.
has a wide field of view.
114. Infra red detectors can work by measuring
radioactive particles.
the temperature rise in a material.
Cerenkov radiation.
energetic charged particles.
115. Wave particle-duality relates to
infra-red radiation.
all of the above.
visible radiation.
UV radiation.
116. The International Ultraviolet Explorer (IUE) experiment
is currently in orbit.
is currently being built.
is not a space mission.
has since finished operation.
117. Scintillation detectors can be made from
wood.
aluminium.
water.
stainless steel.
118. The typical wavelength of an X-ray photon is
50 nm.
600 nm.
0.1 nm.
1.5 µm.
119. A light wave with large amplitude has a
high frequency.
low brightness.
long wavelength.
high brightness.
120. Radio telescopes
require a very smooth surface.
do not require a very smooth surface.
operate only at night.
need to be cooled.
121. The ISO satellite is sensitive to
X-rays.
UV.
IR.
Gamma rays.
122. A Newtonian telescope utilises a
curved secondary mirror.
corrector plate.
flat secondary mirror.
lens.
123. A prime focus telescope represents a feasible optical configuration
when the diameter of the prime mirror is very large.
for amateur telescopes.
when interference is used.
when the focal length is very long.
124. Which of the following parameters is the same for all electromagnetic waves propagating in a vacuum?
Amplitude
Speed
Colour
Wavelength
125. Which of the following statements correctly describes the wavelength of an electromagnetic wave?
The wavelength is the distance between a trough and a peak.
The wavelength is the distance travelled by the wave in 1 second.
The wavelength is the distance travelled by the wave in a short time.
The wavelength is the distance between two consecutive peaks.
126. Interference between the light coming from different telescopes is used to
improve the light spectrum.
improve the light gathering.
improve the magnification.
improve the resolution.
127. Why does a light ray bend when it crosses the boundary between two different media at an oblique angle?
Because it interferes with the surface.
Because the amplitude is reduced.
Because the frequency increases.
Because the speed of light changes.
128. A Newtonian telescope has
a correction plate
just the primary mirror
a flat secondary mirror
a diverging secondary mirror
129. With respect to a dim light, a bright light emits
photons with higher amplitude.
photons with shorter wavelength.
more photons.
photons with longer wavelength.
130. The Hubble telescope was placed in space in order
to be close to the stars.
to not be limited by the Earth’s horizon.
to improve the magnification.
to not be limited by the Earth’s atmosphere.
131. An electromagnetic wave with a wavelength of 100 nm is
visible radiation.
microwave radiation.
UV radiation.
IR radiation.
132. The angular size of the Moon is
18 degrees
1.8 degrees
1 800 arcseconds
1 800 arcminutes
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