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 between a trough and a peak.
The wavelength is the distance travelled by the wave in a short time.
The wavelength is the distance between two consecutive peaks.
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 it interferes with the surface.
Because the frequency increases.
Because the amplitude is reduced.
3. A Newtonian telescope has
just the primary mirror
a flat secondary mirror
a correction plate
a diverging secondary mirror
4. As light passes from one medium to another, its direction of travel changes. What is the name of this effect?
Refraction
Diffraction
Dispersion
Interference
5. Diffraction gratings are used to
break up light into a spectrum.
detect infrared radiation.
reduce diffraction of telescopes.
increase the resolution of telescopes.
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
detecting microwave radiation.
reducing the diffraction of telescopes.
increasing the angular resolution of telescopes.
analysing the light spectrum.
8. Which of the following parameters is the same for all electromagnetic waves propagating in a vacuum?
Wavelength
Colour
Amplitude
Speed
9. Which of the following parameters is the same for all electromagnetic waves propagating in a vacuum?
Colour
Amplitude
Speed
Wavelength
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 speed of light changes.
Because the frequency increases.
Because it interferes with the surface.
11. A Newtonian telescope has
a correction plate.
just the primary mirror.
a diverging secondary mirror.
a flat 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.
ultraviolet radiation.
microwave radiation.
infrared radiation.
14. Which of the following uses a grazing incidence telescope?
International Ultraviolet Explorer.
International Space Observatory.
Chandra X-ray satellite.
International Space Station.
15. The angle through which a ray of light is bent by a glass prism depends on the
wavelength of the light.
reflectivity of the prism.
photoelectric effect.
brightness of the light.
16. The focal length of an ideal mirror depends on
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 arcminutes
0.5 arcseconds
0.5 degrees
19. Which of the following space-based telescopes detected water in the Orion nebula?
The International Space Observatory (ISO)
Hubble
Chandra
The International Ultraviolet Explorer (IUE)
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 increased by a factor of four.
The light gathering power is increased by a factor of two.
The light gathering power is decreased by a factor of four.
21. For a telescope the objective focal length is 80 cm and the eyepiece focal length is 2 cm, what is the magnification?
78
40
less than 1
160
22. To detect dim objects a telescope needs
large diameter.
a long tube.
high magnification.
high resolution.
23. A Charge Coupled Device is used in telescopes to
reduce the effect of segmentation of mirrors.
compensate for sagging of the mirror.
detect light.
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.
image neutrinos.
remove the effect of Cerenkov radiation.
improve the resolution of objects.
25. Karl Jansky was the pioneer of
UV astronomy.
optical astronomy
radio astronomy.
infra-red astronomy.
26. The LIGO gravitational wave detectors
are bar detectors.
have arm lengths of 4 km.
are currently under construction.
have arm lengths of 600 m.
27. Cerenkov radiation is given off when
an electron is ionised from an atom
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 recombines with an ionised atom
28. Why is the colour of the sun during sunset red?
The scattering of blue light is stronger than red light.
The refraction of light is different. Blue light is more strongly refracted.
The 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.
29. 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.
Splitting of the atomic nuclei.
Infra-Red radiation is not absorbed.
30. The ISO satellite is sensitive to
X-rays.
UV.
Gamma rays.
IR.
31. The objective of a telescope is
the adaptor between the telescope and the human eye.
the part of it which first converges the light.
the object under observation.
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
Interference
Dispersion
Diffraction
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 changes in temperature caused 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?
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
absorption.
scattering.
refraction.
diffusion.
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 Cassegrain design
a Schmidt-Cassegrain design
a prime focus arrangement
a grazing incidence mirror
38. The ISO satellite is sensitive to
Gamma rays.
IR.
UV.
X-rays.
39. Why are neutrinos so hard to detect in astronomical observatories?
There are no astronomical sources of neutrinos.
The neutrinos decay before reaching the Earth.
The neutrinos interact only weakly.
Neutrinos are absorbed in the upper atmosphere.
40. The Chandra Observatory is an observatory for
Neutrino astronomy.
X-Ray astronomy.
Radio astronomy.
Infra-red astronomy.
41. Why are astronomers interested in different parts of the spectrum?
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:
gamma radiation.
infrared radiation.
visible 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
x-rays.
gamma rays.
visible light.
gravitational waves.
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 underground in the USA
is located in the Mediterranean sea
is located underground in Japan
is a future planned detector in Japan
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
an electron recombines with an ionised atom
a particle is travelling faster than the speed of light in a medium
48. The typical sensitivity of interferometric gravitational wave detectors is of the order
1 attometer
1 nanometer
1 millimeter
1 micrometer
49. The Compton Gamma Ray Observatory
uses a large tank of water as a scintillation detector
has imaging CCDis
has instruments to look at multiple energy bands
has grazing incidence mirrors to focus the high energy gamma rays
50. Radio telescopes
do not require a very smooth surface.
require a very smooth surface.
need to be cooled.
operate only at night.
51. LIGO is an acronym for:
Light Incident Gravitational Observation.
Laser Interferometric Gravitational-wave Observatory.
Light Ingoing Ground Observations.
Laser Incoming Ground Observation.
52. Long Baseline Interferometry is a technique often used in radio astronomy to
remove the effect of Cerenkov radiation.
image neutrinos.
reduce the effect of light pollution in urban skies.
improve the resolution of objects.
53. Chromatic aberration can occur in a telescope because
the telescope is not stable.
light of different wavelengths are focussed to different positions.
light of different wavelengths are reflected to different positions.
the atmosphere is not stable.
54. The speed of light in a vacuum is approximately
30 million metres per second.
30 thousand metres per second.
300 million metres per second.
300 thousand 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 thickness of the mirror.
the diameter of the mirror.
the distance from the mirror to an object.
the distance from the mirror to the focal point.
57. Light can be described as having a "dual" nature. What does this mean?
It has brightness and wavelength.
It can go fast and slow.
It behaves like a wave and a particle.
It travels in two directions at the same time.
58. A Newtonian telescope is
a reflecting telescope.
a refracting telescope.
a Cassegrain telescope.
a prime focus telescope.
59. Astronomers hope to discover gravitational waves by
using highly-sensitive CCD sensors.
placing radio telescopes in space.
using laser interferometers.
detecting high-energy gamma rays.
60. During the day the sky appears blue because
the scattering of blue light is stronger than red light.
blue light is refracted less than red light.
the atmosphere reflects more red light from the Sun during the day.
the Sun changes colour over a period of 24 hours.
61. Atmospheric absorption causes
the light from stars to appear stronger than it should.
the scattering of light with large wavelengths.
the stars to twinkle in appearance.
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.
putting the telescope on a mountain.
increasing the diameter of the primary mirror.
making observations during the night.
63. A Schmidt-Cassegrain telescope is one that has?
A corrector plate and a primary mirror only.
A corrector plate, a primary mirror and a secondary mirror.
Only mirrors.
Only lenses.
64. Why are astronomers interested in measuring light at different parts of the electromagnetic spectrum?
Stars emit mainly ultraviolet radiation.
Because in vacuum light travels at different speeds at different wavelengths.
Because visible light is hard to detect on Earth.
Different parts of the spectrum provide different information.
65. What does the frequency of light mean?
How bright the light will be.
The number of times the wave cycle repeats every second.
The distance from one maximum to another.
The distance it will travel in 1 second.
66. The energy of a photon can be expressed by
E=hf.
E=f/λ.
E=cλ.
E=hc.
67. What is the purpose of the objective lens in a refracting telescope?
To diffract the incoming light.
To focus the incoming light.
To change the speed of the incoming light.
To interfere 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
change the detector sensitivity for measuring different wavelengths.
change the focal length of the primary mirror for different astronomical objects.
change the shape of the primary mirror to correct for atmospheric disturbances.
maximise the light gathering power of the telescope.
70. The Earth’s atmosphere is responsible for which three phenomena in observational astronomy?
Atmospheric refraction, Atmospheric scattering, and Atmospheric absorption.
Atmospheric diffraction, Chromatic aberration, and Atmospheric scattering.
Wave particle duality, Atmospheric scattering, and Atmospheric absorption.
Atmospheric scattering, Spherical aberration, and Atmospheric refraction.
71. For what reason is interferometry used when using multiple telescopes to observe astronomical objects?
To increase the resolving power of the detector.
To measure different frequencies of light simultaneously.
To remove the effect of light pollution.
To reduce the magnification.
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?
Red light has a longer wavelength than blue light.
Light travels faster in glass than in a vacuum.
Light is both a wave and a particle.
Light is a wave of varying electric and magnetic fields.
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, Resolving Power.
Magnification, Diffractive Power, Light Gathering Power.
Diffractive Power, Light Gathering Power, Resolving Power.
Magnification, Light Gathering 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 red light is absorbed by the atmosphere.
Because the sky reflects the blue colour of the sea.
Because blue light is scattered more than red light.
79. Grazing incidence mirrors are used to focus light in what type of telescope?
X-Ray telescopes.
Optical telescopes.
Radio telescopes.
Infra-red telescopes.
80. By what method are radio telescopes able to obtain high-resolution images?
By using the interference of signals from many radio telescopes.
By using laser guide adaptive optics.
By using computer grinding to construct very smooth mirrors.
By having a large field of view.
81. Super-Kamiokande is an experiment designed to detect what?
Gamma rays.
Neutrinos.
Earth-like planets.
Gravitational waves.
82. The James Webb telescope is intended to replace what?
The Hubble Space telescope.
The Infra Red Astronomical Satellite.
The Compton Gamma Ray observatory.
The Chandra observatory.
83. Which of the following is a true statement?
Light is neither a wave nor a particle.
Light is a wave, but not a particle.
Light is 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?
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
Refraction
Interference
Dispersion
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 Coupled Device.
Charge Coupled Diode.
Count Collecting Device.
Charge Collecting Diode.
88. Ultra-Violet (UV) radiation is emitted by objects of temperature around
1 000 000 K
10,000 K
500 K
10 K
89. The Chandra Observatory is an observatory for
Neutrino astronomy.
Radio astronomy.
X-Ray astronomy.
Infra-red 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 interact only weakly.
Neutrinos are absorbed in the upper atmosphere.
There are no astronomical sources of neutrinos.
The neutrinos decay before reaching the Earth.
92. Which of the following is NOT a good source of gravitational waves?
Magellanic clouds.
Black Hole binary systems.
Pulsars.
Supernova explosions.
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 red light is transmitted through the grating because only blue light is scattered.
The outcoming light stays blue.
Nothing. Diffraction is wavelength-independent.
The angle between the diffraction orders becomes larger.
94. Which statement is wrong?
The energy of photons is just dependent on the frequency.
Light travels always with a constant speed.
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?
They have no aberration.
Mirrors are easier to make and to mount.
Lenses cannot be used for visible light.
It is not possible to melt enough glass to fabricate a large lens.
96. Why are astronomers interested in different parts of the spectrum?
Different parts of the spectrum contain different information.
At some locations at the sky certain detectors do not work.
The different colours are nice.
The results would otherwise interfere destructively.
97. A Cassegrain telescope may have a focal length of 100 cm. The diameter of the mirror shall be 25 cm. The eyepiece used in this configuration has a focal length of 1 cm and a diameter of 0.5 cm. What magnification is achieved?
It is not possible to calculate the magnification with these parameters.
A magnification of 50.
A magnification of 25.
A magnification of 100.
98. Why is the colour of the sun during sunset red?
The scattering of blue light is stronger than red light.
The diffraction of light is different. Blue light is more strongly diffracted.
The refraction of light is different. Blue light is more strongly refracted.
The sun changes its colour in 24 h from blue to red and back to blue.
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.
They are based on the photoelectric effect: light kicks out electrons from the material.
They are not used. The IR part of the spectrum does not contain any information.
The electrons in the detector need to get some additional energy to be used for detection. Thus, these detectors need to be heated.
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.
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.
101. What can be observed with radio astronomy?
Wavelengths that are in the region of cm.
The moon.
Radio broadcast of other civilizations in the universe.
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 will allow a very high resolution when combining a gravitational wave telescope with a CCD.
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.
103. Adaptive optics is a technique that reduces the effect of atmospheric turbulence by
evacuating the telescope tube.
adjusting the eyepiece position
varying the mirror reflectivity.
bending the telescope mirror.
104. The angular size of the Moon is
5 degrees.
0.5 degree.
0.1 degree
50 degrees.
105. Which of the following uses a grazing incidence telescope?
Spitzer.
Hubble Space telescope.
International Ultraviolet Explorer.
Chandra.
106. Modern observatories mostly use
photographic film.
observatories at low altitude.
refractive objectives.
CCD detectors.
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.
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?
Infra-Red radiation is not absorbed.
Splitting of the atomic nuclei.
Breaking of the chemical bonds.
Excitation of vibrational modes of molecules.
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:
infrared radiation.
ultra-violet radiation.
gamma radiation.
visible 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.
speed of the light.
wavelength 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.
has a short focal length.
is not a widely used optical design.
114. Infra red detectors can work by measuring
radioactive particles.
the temperature rise in a material.
energetic charged particles.
Cerenkov radiation.
115. Wave particle-duality relates to
infra-red radiation.
UV radiation.
visible radiation.
all of the above.
116. The International Ultraviolet Explorer (IUE) experiment
is currently in orbit.
is currently being built.
has since finished operation.
is not a space mission.
117. Scintillation detectors can be made from
wood.
water.
aluminium.
stainless steel.
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
low brightness.
high frequency.
high brightness.
long wavelength.
120. Radio telescopes
operate only at night.
need to be cooled.
require a very smooth surface.
do not require a very smooth surface.
121. The ISO satellite is sensitive to
X-rays.
UV.
IR.
Gamma rays.
122. A Newtonian telescope utilises a
flat secondary mirror.
lens.
corrector plate.
curved secondary mirror.
123. A prime focus telescope represents a feasible optical configuration
when the focal length is very long.
when interference is used.
when the diameter of the prime mirror is very large.
for amateur telescopes.
124. Which of the following parameters is the same for all electromagnetic waves propagating in a vacuum?
Wavelength
Colour
Amplitude
Speed
125. Which of the following statements correctly describes the wavelength of an electromagnetic wave?
The wavelength is the distance travelled by the wave in 1 second.
The wavelength is the distance travelled by the wave in a short time.
The wavelength is the distance between a trough and a peak.
The wavelength is the distance between two consecutive peaks.
126. Interference between the light coming from different telescopes is used to
improve the light spectrum.
improve the resolution.
improve the magnification.
improve the light gathering.
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 frequency increases.
Because the speed of light changes.
Because the amplitude is reduced.
128. A Newtonian telescope has
just the primary mirror
a correction plate
a flat secondary mirror
a diverging secondary mirror
129. With respect to a dim light, a bright light emits
photons with shorter wavelength.
more photons.
photons with longer wavelength.
photons with higher amplitude.
130. The Hubble telescope was placed in space in order
to be close to the stars.
to not be limited by the Earth’s horizon.
to not be limited by the Earth’s atmosphere.
to improve the magnification.
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 arcseconds
1.8 degrees
1 800 arcminutes
18 degrees
133. Hello
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