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