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 frequency increases.
Because the speed of light changes.
Because it interferes with the surface.
Because the amplitude is reduced.
3. A Newtonian telescope has
a flat secondary mirror
just the primary 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?
Dispersion
Refraction
Diffraction
Interference
5. Diffraction gratings are used to
increase the resolution of telescopes.
reduce diffraction of telescopes.
break up light into a spectrum.
detect infrared radiation.
6. The speed of light in glass is
the same as in vacuum
reduced by approximately 1%
increased by approximately 50%
reduced by approximately 60%
7. Diffraction gratings are used for
increasing the angular resolution of telescopes.
reducing the diffraction of telescopes.
detecting microwave radiation.
analysing the light spectrum.
8. Which of the following parameters is the same for all electromagnetic waves propagating in a vacuum?
Wavelength
Amplitude
Speed
Colour
9. Which of the following parameters is the same for all electromagnetic waves propagating in a vacuum?
Colour
Speed
Wavelength
Amplitude
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 amplitude is reduced.
Because the speed of light changes.
11. A Newtonian telescope has
a correction plate.
a diverging secondary mirror.
just the primary mirror.
a flat secondary mirror.
12. The Hubble telescope was placed in space in order
to not be limited by the Earth’s horizon.
to improve the magnification.
to be close to the stars.
to not be limited by the Earth’s atmosphere.
13. An electromagnetic wave with a wavelength of 600 nm is
infrared radiation.
visible radiation.
microwave radiation.
ultraviolet radiation.
14. Which of the following uses a grazing incidence telescope?
International Space Station.
International Space Observatory.
Chandra X-ray satellite.
International Ultraviolet Explorer.
15. The angle through which a ray of light is bent by a glass prism depends on the
reflectivity of the prism.
wavelength of the light.
brightness of the light.
photoelectric effect.
16. The focal length of an ideal mirror depends on
brightness of the light.
reflectivity of the prism.
photoelectric effect.
wavelength of the light.
17. Light can be described as having a “dual†nature. What does this mean?
Light can be expressed as brightness and colour.
If light moves in one direction, then it moves in the opposite direction also.
Light goes slow and fast.
Light behaves like a wave and like a particle.
18. What is the angular size of the Moon?
0.5 degrees
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)
Chandra
Hubble
The International Space Observatory (ISO)
20. If the width of the objective of a telescope is doubled, what happens to its light gathering power?
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.
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?
less than 1
40
160
78
22. To detect dim objects a telescope needs
high resolution.
high magnification.
large diameter.
a long tube.
23. A Charge Coupled Device is used in telescopes to
detect light.
reduce the effect of segmentation of mirrors.
compensate for sagging of the mirror.
improve light gathering.
24. 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.
25. Karl Jansky was the pioneer of
optical astronomy
UV astronomy.
radio astronomy.
infra-red astronomy.
26. The LIGO gravitational wave detectors
have arm lengths of 4 km.
are currently under construction.
have arm lengths of 600 m.
are bar detectors.
27. 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
28. Why is the colour of the sun during sunset red?
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.
The refraction of light is different. Blue light is more strongly refracted.
29. 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.
30. The ISO satellite is sensitive to
UV.
Gamma rays.
IR.
X-rays.
31. The objective of a telescope is
the object under observation.
the part of it which first converges the light.
the reason why that telescope has been buil
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?
Interference
Diffraction
Refraction
Dispersion
33. How does an infrared telescope make detections?
By directly detecting the number of incident photons.
By monitoring changes in temperature caused by incident photons.
By detecting oscillating electric signals generated by incident photons.
By monitoring the number of electrons released by incident photons.
34. Which of the following processes is responsible for absorption of infrared radiation by the atmosphere?
The breaking of chemical bonds in ozone.
Interaction of the radiation with the nuclei of atoms in the atmosphere.
Conduction in an upper part of the atmosphere.
The excitation of the vibrational modes of water vapour molecules.
35. The twinkling of the stars is due to
absorption.
refraction.
scattering.
diffusion.
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 prime focus arrangement
a grazing incidence mirror
a Cassegrain design
a Schmidt-Cassegrain design
38. The ISO satellite is sensitive to
X-rays.
IR.
UV.
Gamma rays.
39. 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.
40. The Chandra Observatory is an observatory for
Neutrino astronomy.
Radio astronomy.
Infra-red astronomy.
X-Ray astronomy.
41. Why are astronomers interested in different parts of the spectrum?
The different colours are nice.
Different parts of the spectrum contain different information.
The results would otherwise interfere destructively.
At some locations at the sky certain detectors do not work.
42. An electromagnetic wave having a wavelength of 550 nm is:
gamma radiation.
visible radiation.
infrared radiation.
ultra-violet radiation.
43. Karl Jansky was the pioneer of
optical astronomy.
radio astronomy.
infra-red astronomy.
UV astronomy.
44. A grazing incidence mirror is used to focus
visible light.
x-rays.
gamma rays.
gravitational waves.
45. Modern observatories are placed on mountains
to get closer to the stars
because it is cheaper to build them on mountains
to be able to observe X-rays
to reduce the amount of turbulent atmosphere
46. The Super Kamiokande Neutrino observatory
is a future planned detector in Japan
is located underground in the USA
is located in the Mediterranean sea
is located underground in Japan
47. 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
48. The typical sensitivity of interferometric gravitational wave detectors is of the order
1 attometer
1 nanometer
1 micrometer
1 millimeter
49. The Compton Gamma Ray Observatory
has imaging CCDis
has instruments to look at multiple energy bands
uses a large tank of water as a scintillation detector
has grazing incidence mirrors to focus the high energy gamma rays
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:
Light Incident Gravitational Observation.
Light Ingoing Ground Observations.
Laser Incoming Ground Observation.
Laser Interferometric Gravitational-wave Observatory.
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
light of different wavelengths are reflected to different positions.
the atmosphere is not stable.
the telescope is not stable.
light of different wavelengths are focussed to different positions.
54. The speed of light in a vacuum is approximately
300 thousand metres per second.
300 million metres per second.
30 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.
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 diameter of the mirror.
the distance from the mirror to the focal point.
the thickness 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 travels in two directions at the same time.
It behaves like a wave and a particle.
It can go fast and slow.
It has brightness and wavelength.
58. A Newtonian telescope is
a prime focus telescope.
a reflecting telescope.
a refracting telescope.
a Cassegrain telescope.
59. Astronomers hope to discover gravitational waves by
using highly-sensitive CCD sensors.
using laser interferometers.
detecting high-energy gamma rays.
placing radio telescopes in space.
60. During the day the sky appears blue because
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.
the scattering of blue light is stronger than red light.
61. Atmospheric absorption causes
dimming or extinction of certain wavelengths of light.
the scattering of light with large wavelengths.
the light from stars to appear stronger than it should.
the stars to twinkle in appearance.
62. The resolving power of a radio telescope can be increased by
putting the telescope on a mountain.
decreasing the diameter of the primary mirror.
making observations during the night.
increasing the diameter of the primary mirror.
63. A Schmidt-Cassegrain telescope is one that has?
Only lenses.
A corrector plate and a primary mirror only.
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?
Stars emit mainly ultraviolet radiation.
Different parts of the spectrum provide different information.
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?
How bright the light will be.
The distance it will travel in 1 second.
The distance from one maximum to another.
The number of times the wave cycle repeats every second.
66. The energy of a photon can be expressed by
E=f/λ.
E=hc.
E=cλ.
E=hf.
67. What is the purpose of the objective lens in a refracting telescope?
To interfere the incoming light.
To change the speed of the incoming light.
To focus 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 = 100.
M = 1/100.
M = 3/300.
M = 300.
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 scattering, Spherical aberration, and Atmospheric refraction.
Wave particle duality, Atmospheric scattering, and Atmospheric absorption.
Atmospheric diffraction, Chromatic aberration, and Atmospheric scattering.
Atmospheric refraction, Atmospheric scattering, and Atmospheric absorption.
71. For what reason is interferometry used when using multiple telescopes to observe astronomical objects?
To increase the resolving power of the detector.
To remove the effect of light pollution.
To measure different frequencies of light simultaneously.
To reduce the magnification.
72. Gravitational wave detectors aim to measure the radiation emitted by accelerating masses by
using multiple radio telescopes around the world.
using the James Webb Space Telescope.
detecting Cherenkov radiation with photomultiplier tubes.
using long-baseline laser interferometers.
73. Which of the following statements is false?
Light is both a wave and a particle.
Light travels faster in glass than in a vacuum.
Red light has a longer wavelength than blue light.
Light is a wave of varying electric and magnetic fields.
74. A Schmidt-Cassegrain telescope uses which of the following components?
Both lenses and mirrors.
A diffraction grating.
Only 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?
270
30
1/30
60
76. What are the three important qualities of a telescope?
Magnification, Light Gathering Power, Resolving Power.
Diffractive Power, Light Gathering Power, Resolving Power.
Magnification, Diffractive Power, Light Gathering 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?
Infra-red telescopes.
X-Ray telescopes.
Optical telescopes.
Radio 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 laser guide adaptive optics.
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?
Gamma rays.
Neutrinos.
Gravitational waves.
Earth-like planets.
82. The James Webb telescope is intended to replace what?
The Infra Red Astronomical Satellite.
The Hubble Space telescope.
The Chandra observatory.
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?
Visible red light.
Microwaves.
Radio waves.
X-Rays.
85. What is the phenomenon where the velocity of light in a medium depends on its wavelength?
Diffraction
Dispersion
Interference
Refraction
86. Newton's telescope was a
Cassegrain telescope.
reflecting telescope.
refracting telescope.
prime focus 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.
X-Ray astronomy.
Radio astronomy.
Neutrino astronomy.
90. Why can X-Rays penetrate inside solids?
They are of very small frequency.
They are very non-reactive.
They have very small wavelengths.
They are out of phase with ordinary matter.
91. Why are neutrinos so hard to detect in astronomical observatories?
The neutrinos interact only weakly.
There are no astronomical sources of neutrinos.
The neutrinos decay before reaching the Earth.
Neutrinos are absorbed in the upper atmosphere.
92. Which of the following is NOT a good source of gravitational waves?
Pulsars.
Black Hole binary systems.
Supernova explosions.
Magellanic clouds.
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 travels with different speeds depending on the material.
The energy of photons is just dependent on the frequency.
Light has a constant speed in vacuum.
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.
It is not possible to melt enough glass to fabricate a large lens.
They have no aberration.
Mirrors are easier to make and to mount.
96. Why are astronomers interested in different parts of the spectrum?
The different colours are nice.
Different parts of the spectrum contain different information.
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 50.
A magnification of 100.
A magnification of 25.
98. Why is the colour of the sun during sunset red?
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.
The diffraction of light is different. Blue light is more strongly diffracted.
99. What is true for an IR detector used in astronomy?
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.
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.
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.
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 in the region of cm.
The moon.
Wavelengths that are shorter than the visible light.
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.
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.
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.
0.1 degree
0.5 degree.
50 degrees.
105. Which of the following uses a grazing incidence telescope?
Hubble Space telescope.
Chandra.
International Ultraviolet Explorer.
Spitzer.
106. Modern observatories mostly use
photographic film.
CCD detectors.
refractive objectives.
observatories at low altitude.
107. LIGO is an acronym for:
Light Incident Gravitational Observation.
Laser Incoming Ground Observation.
Light Ingoing Ground Observations.
Laser Interferometric Gravitational-wave Observatory.
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.
remains the same.
is increased by a factor of three.
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.
Excitation of vibrational modes of molecules.
Infra-Red radiation is not absorbed.
Breaking of the chemical bonds.
110. Long Baseline Interferometry is a technique often used in radio astronomy to
improve the resolution of objects.
remove the effect of Cerenkov radiation.
reduce the effect of light pollution in urban skies.
image neutrinos.
111. An electromagnetic wave having a wavelength of 550 nm is:
ultra-violet radiation.
infrared radiation.
visible radiation.
gamma radiation.
112. In a diffraction grating the angle between the zero order (white fringe) and first order (coloured fringe) depends on the
intensity of the light.
wavelength of the light.
brightness of the light.
speed of the light.
113. A Cassegrain telescope
has a short focal length.
is not a widely used optical design.
is a common optical design used at modern observatories.
has a wide field of view.
114. Infra red detectors can work by measuring
the temperature rise in a material.
Cerenkov radiation.
energetic charged particles.
radioactive 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 not a space mission.
is currently being built.
has since finished operation.
is currently in orbit.
117. Scintillation detectors can be made from
wood.
stainless steel.
aluminium.
water.
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
high frequency.
high brightness.
low brightness.
long wavelength.
120. Radio telescopes
do not require a very smooth surface.
require a very smooth surface.
need to be cooled.
operate only at night.
121. The ISO satellite is sensitive to
Gamma rays.
X-rays.
IR.
UV.
122. A Newtonian telescope utilises a
lens.
curved secondary mirror.
flat secondary mirror.
corrector plate.
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.
for amateur telescopes.
when interference is used.
124. Which of the following parameters is the same for all electromagnetic waves propagating in a vacuum?
Speed
Amplitude
Wavelength
Colour
125. 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.
126. Interference between the light coming from different telescopes is used to
improve the light gathering.
improve the resolution.
improve the light spectrum.
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 frequency increases.
Because the speed of light changes.
Because it interferes with the surface.
Because the amplitude is reduced.
128. A Newtonian telescope has
just the primary mirror
a flat secondary mirror
a diverging secondary mirror
a correction plate
129. With respect to a dim light, a bright light emits
more photons.
photons with shorter wavelength.
photons with longer 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
visible radiation.
IR radiation.
microwave radiation.
UV radiation.
132. The angular size of the Moon is
1 800 arcminutes
1 800 arcseconds
1.8 degrees
18 degrees
133. Hello
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