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 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 correction plate
a diverging secondary mirror
a flat secondary mirror
just the primary mirror
4. As light passes from one medium to another, its direction of travel changes. What is the name of this effect?
Interference
Diffraction
Dispersion
Refraction
5. Diffraction gratings are used to
reduce diffraction of telescopes.
increase the resolution of telescopes.
detect infrared radiation.
break up light into a spectrum.
6. The speed of light in glass is
reduced by approximately 1%
the same as in vacuum
reduced by approximately 60%
increased by approximately 50%
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?
Speed
Amplitude
Colour
Wavelength
9. Which of the following parameters is the same for all electromagnetic waves propagating in a vacuum?
Speed
Colour
Wavelength
Amplitude
10. 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 frequency increases.
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 horizon.
to not be limited by the Earth’s atmosphere.
to be close to the stars.
to improve the magnification.
13. An electromagnetic wave with a wavelength of 600 nm is
visible radiation.
ultraviolet radiation.
infrared radiation.
microwave radiation.
14. Which of the following uses a grazing incidence telescope?
International Space Observatory.
International Space Station.
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
photoelectric effect.
reflectivity of the prism.
wavelength of the light.
brightness of the light.
16. The focal length of an ideal mirror depends on
photoelectric effect.
wavelength of the light.
reflectivity of the prism.
brightness 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 behaves like a wave and like a particle.
Light goes slow and fast.
18. What is the angular size of the Moon?
0.5 arcminutes
0.5 arcseconds
0.5 degrees
5 degrees
19. Which of the following space-based telescopes detected water in the Orion nebula?
Chandra
The International Ultraviolet Explorer (IUE)
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 increased by a factor of four.
The light gathering power remains the same.
The light gathering power is decreased by a factor of four.
The light gathering power is increased by a factor of two.
21. For a telescope the objective focal length is 80 cm and the eyepiece focal length is 2 cm, what is the magnification?
40
less than 1
78
160
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.
improve light gathering.
reduce the effect of segmentation of mirrors.
compensate for sagging of the mirror.
24. Long Baseline Interferometry is a technique often used in radio astronomy to
reduce the effect of light pollution in urban skies.
remove the effect of Cerenkov radiation.
improve the resolution of objects.
image neutrinos.
25. Karl Jansky was the pioneer of
optical astronomy
infra-red astronomy.
UV astronomy.
radio astronomy.
26. The LIGO gravitational wave detectors
have arm lengths of 600 m.
are currently under construction.
are bar detectors.
have arm lengths of 4 km.
27. Cerenkov radiation is given off when
an electron recombines with an ionised atom
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
28. Why is the colour of the sun during sunset red?
The refraction of light is different. Blue light is more strongly refracted.
The diffraction of light is different. Blue light is more strongly diffracted.
The 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.
29. 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.
30. The ISO satellite is sensitive to
Gamma rays.
X-rays.
IR.
UV.
31. The objective of a telescope is
the object under observation.
the adaptor between the telescope and the human eye.
the reason why that telescope has been buil
the part of it which first converges the light.
32. As light passes from one medium to another, its direction of travel changes. What is the name of this effect?
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?
The excitation of the vibrational modes of water vapour molecules.
Conduction in an upper part of the atmosphere.
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
refraction.
diffusion.
scattering.
absorption.
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 Schmidt-Cassegrain design
a grazing incidence mirror
a Cassegrain design
a prime focus arrangement
38. The ISO satellite is sensitive to
Gamma rays.
IR.
UV.
X-rays.
39. Why are neutrinos so hard to detect in astronomical observatories?
Neutrinos are absorbed in the upper atmosphere.
The neutrinos decay before reaching the Earth.
The neutrinos interact only weakly.
There are no astronomical sources of neutrinos.
40. The Chandra Observatory is an observatory for
Infra-red astronomy.
X-Ray astronomy.
Neutrino astronomy.
Radio astronomy.
41. Why are astronomers interested in different parts of the spectrum?
Different parts of the spectrum contain different information.
The different colours are nice.
At some locations at the sky certain detectors do not work.
The results would otherwise interfere destructively.
42. An electromagnetic wave having a wavelength of 550 nm is:
infrared radiation.
ultra-violet radiation.
gamma radiation.
visible radiation.
43. Karl Jansky was the pioneer of
optical astronomy.
radio astronomy.
UV astronomy.
infra-red astronomy.
44. A grazing incidence mirror is used to focus
gamma rays.
visible light.
x-rays.
gravitational waves.
45. Modern observatories are placed on mountains
because it is cheaper to build them on mountains
to reduce the amount of turbulent atmosphere
to get closer to the stars
to be able to observe X-rays
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
an electron recombines with an ionised atom
a particle is travelling faster than the speed of light in a medium
an electron is ionised from an atom
a particle is travelling slower than the speed of light in a medium
48. The typical sensitivity of interferometric gravitational wave detectors is of the order
1 nanometer
1 micrometer
1 millimeter
1 attometer
49. The Compton Gamma Ray Observatory
has instruments to look at multiple energy bands
has grazing incidence mirrors to focus the high energy gamma rays
has imaging CCDis
uses a large tank of water as a scintillation detector
50. Radio telescopes
require a very smooth surface.
operate only at night.
do not require a very smooth surface.
need to be cooled.
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.
remove the effect of Cerenkov radiation.
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 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.
30 million metres per second.
300 million metres per second.
55. The term 'refraction' is used to describe when light
changes direction when transmitting through different media.
bends around the edges of objects.
waves add together to produce brighter light.
changes frequency when transmitting through different media.
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 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 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 refracting telescope.
a reflecting telescope.
a prime focus telescope.
a Cassegrain telescope.
59. Astronomers hope to discover gravitational waves by
using laser interferometers.
using highly-sensitive CCD sensors.
detecting high-energy gamma rays.
placing radio telescopes in space.
60. During the day the sky appears blue because
the atmosphere reflects more red light from the Sun during the day.
blue light is refracted less than red light.
the Sun changes colour over a period of 24 hours.
the scattering of blue light is stronger than red light.
61. Atmospheric absorption causes
dimming or extinction of certain wavelengths of light.
the stars to twinkle in appearance.
the light from stars to appear stronger than it should.
the scattering of light with large wavelengths.
62. The resolving power of a radio telescope can be increased by
putting the telescope on a mountain.
making observations during the night.
increasing the diameter of the primary mirror.
decreasing the diameter of the primary mirror.
63. A Schmidt-Cassegrain telescope is one that has?
Only lenses.
A corrector plate and a primary mirror only.
Only mirrors.
A corrector plate, a primary mirror and a secondary mirror.
64. Why are astronomers interested in measuring light at different parts of the electromagnetic spectrum?
Because 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 it will travel in 1 second.
How bright the light will be.
The distance from one maximum to another.
66. The energy of a photon can be expressed by
E=f/λ.
E=hf.
E=cλ.
E=hc.
67. What is the purpose of the objective lens in a refracting telescope?
To focus the incoming light.
To interfere the incoming light.
To diffract 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 = 3/300.
M = 300.
M = 1/100.
M = 100.
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.
maximise the light gathering power of the telescope.
change the focal length of the primary mirror for different astronomical objects.
70. The Earth’s atmosphere is responsible for which three phenomena in observational astronomy?
Wave particle duality, Atmospheric scattering, and Atmospheric absorption.
Atmospheric scattering, Spherical aberration, and Atmospheric refraction.
Atmospheric refraction, Atmospheric scattering, and Atmospheric absorption.
Atmospheric diffraction, Chromatic aberration, and Atmospheric scattering.
71. For what reason is interferometry used when using multiple telescopes to observe astronomical objects?
To reduce the magnification.
To measure different frequencies of light simultaneously.
To remove the effect of light pollution.
To increase the resolving power of the detector.
72. Gravitational wave detectors aim to measure the radiation emitted by accelerating masses by
using multiple radio telescopes around the world.
using long-baseline laser interferometers.
detecting Cherenkov radiation with photomultiplier tubes.
using the James Webb Space Telescope.
73. Which of the following statements is false?
Light is a wave of varying electric and magnetic fields.
Light travels faster in glass than in a vacuum.
Red light has a longer wavelength than blue light.
Light is both a wave and a particle.
74. A Schmidt-Cassegrain telescope uses which of the following components?
Only mirrors.
Only lenses.
A diffraction grating.
Both lenses and mirrors.
75. If a telescope has an objective with a focal length of 90 cm and an eyepiece with focal length of 3 cm, what is the magnification of the telescope?
60
1/30
270
30
76. What are the three important qualities of a telescope?
Magnification, Diffractive Power, Resolving Power.
Magnification, Light Gathering Power, Resolving Power.
Diffractive Power, Light Gathering Power, Resolving Power.
Magnification, Diffractive Power, Light Gathering Power.
77. What causes the twinkling of stars?
The variation in intensity of light emitted by the star.
Atmospheric Dispersion.
Impurities in the lens of the telescope or eye.
Atmospheric refraction.
78. On a cloudless day, why does the sky look blue?
Because the sky reflects the blue colour of the sea.
Because blue light is scattered more than red light.
Because red light is scattered more than blue 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.
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 laser guide adaptive optics.
By using the interference of signals from many radio telescopes.
By using computer grinding to construct very smooth mirrors.
81. Super-Kamiokande is an experiment designed to detect what?
Neutrinos.
Earth-like planets.
Gravitational waves.
Gamma rays.
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 a particle, but not a wave.
Light is neither a wave nor a particle.
Light is both a wave and a particle.
84. Which of the following describes waves whose wavelength is approximately 1 mm?
Visible red light.
Radio waves.
Microwaves.
X-Rays.
85. What is the phenomenon where the velocity of light in a medium depends on its wavelength?
Diffraction
Refraction
Dispersion
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
500 K
10 K
1 000 000 K
10,000 K
89. The Chandra Observatory is an observatory for
Radio astronomy.
Neutrino astronomy.
X-Ray astronomy.
Infra-red astronomy.
90. Why can X-Rays penetrate inside solids?
They have very small wavelengths.
They are of very small frequency.
They are out of phase with ordinary matter.
They are very non-reactive.
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?
Magellanic clouds.
Black Hole binary systems.
Supernova explosions.
Pulsars.
93. A reflective diffraction grating is separating the light colours and creates a spectrum. What happens if the incoming light is changed from blue to red?
The angle between the diffraction orders becomes larger.
The red light is transmitted through the grating because only blue light is scattered.
Nothing. Diffraction is wavelength-independent.
The outcoming light stays blue.
94. Which statement is wrong?
Light travels always with a constant speed.
The energy of photons is just dependent on the frequency.
Light travels with different speeds depending on the material.
Light has a constant speed in vacuum.
95. Why are most of the modern telescopes for visible light reflecting telescopes?
Mirrors are easier to make and to mount.
It is not possible to melt enough glass to fabricate a large lens.
Lenses cannot be used for visible light.
They have no aberration.
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?
A magnification of 50.
A magnification of 25.
A magnification of 100.
It is not possible to calculate the magnification with these parameters.
98. Why is the colour of the sun during sunset red?
The refraction of light is different. Blue light is more strongly refracted.
The diffraction of light is different. Blue light is more strongly diffracted.
The scattering of blue light is stronger than red light.
The sun changes its colour in 24 h from blue to red and back to blue.
99. What is true for an IR detector used in astronomy?
Light is absorbed and the temperature increase is measured. Therefore, it is good to cool them.
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.
They are based on the photoelectric effect: light kicks out electrons from the material.
100. What is the reason why X-ray telescopes are so much different from telescopes for the visible part of the spectrum?
It is too dangerous to observe X-rays from astronomical objects.
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.
Materials are nearly transparent in the X-ray band. Standard optical configurations cannot be used.
101. What can be observed with radio astronomy?
Radio broadcast of other civilizations in the universe.
Wavelengths that are in the region of cm.
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.
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
evacuating the telescope tube.
varying the mirror reflectivity.
bending the telescope mirror.
adjusting the eyepiece position
104. The angular size of the Moon is
0.1 degree
5 degrees.
50 degrees.
0.5 degree.
105. Which of the following uses a grazing incidence telescope?
Hubble Space telescope.
International Ultraviolet Explorer.
Chandra.
Spitzer.
106. Modern observatories mostly use
CCD detectors.
photographic film.
observatories at low altitude.
refractive objectives.
107. LIGO is an acronym for:
Laser Incoming Ground Observation.
Light Incident Gravitational 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 two.
is increased by a factor of three.
is increased by a factor of four.
remains the same.
109. Which of the following processes is responsible for the absorption of Infra-Red radiation?
Splitting of the atomic nuclei.
Infra-Red radiation is not absorbed.
Excitation of vibrational modes of molecules.
Breaking of the chemical bonds.
110. Long Baseline Interferometry is a technique often used in radio astronomy to
reduce the effect of light pollution in urban skies.
remove the effect of Cerenkov radiation.
improve the resolution of objects.
image neutrinos.
111. An electromagnetic wave having a wavelength of 550 nm is:
gamma radiation.
infrared radiation.
visible 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
speed of the light.
intensity of the light.
wavelength of the light.
brightness of the light.
113. A Cassegrain telescope
has a short focal length.
is a common optical design used at modern observatories.
has a wide field of view.
is not a widely used optical design.
114. Infra red detectors can work by measuring
energetic charged particles.
Cerenkov radiation.
the temperature rise in a material.
radioactive particles.
115. Wave particle-duality relates to
UV radiation.
infra-red radiation.
visible 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
water.
wood.
stainless steel.
aluminium.
118. The typical wavelength of an X-ray photon is
50 nm.
0.1 nm.
600 nm.
1.5 µm.
119. A light wave with large amplitude has a
low brightness.
high frequency.
high brightness.
long wavelength.
120. Radio telescopes
require a very smooth surface.
do not require a very smooth surface.
need to be cooled.
operate only at night.
121. The ISO satellite is sensitive to
IR.
UV.
Gamma rays.
X-rays.
122. A Newtonian telescope utilises a
lens.
corrector plate.
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 interference is used.
for amateur telescopes.
when the focal length is very long.
124. Which of the following parameters is the same for all electromagnetic waves propagating in a vacuum?
Colour
Amplitude
Speed
Wavelength
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 spectrum.
improve the magnification.
improve the light gathering.
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 speed of light changes.
Because the frequency increases.
Because the amplitude is reduced.
128. A Newtonian telescope has
just the primary mirror
a diverging secondary mirror
a flat secondary mirror
a correction plate
129. With respect to a dim light, a bright light emits
more photons.
photons with higher amplitude.
photons with longer wavelength.
photons with shorter wavelength.
130. 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.
131. An electromagnetic wave with a wavelength of 100 nm is
microwave radiation.
IR radiation.
UV radiation.
visible radiation.
132. The angular size of the Moon is
18 degrees
1 800 arcminutes
1 800 arcseconds
1.8 degrees
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