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