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