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 a trough and a peak.
The wavelength is the distance travelled by the wave in a short time.
The wavelength is the distance travelled by the wave in 1 second.
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
a flat secondary mirror
just the primary 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?
Interference
Dispersion
Diffraction
Refraction
5. Diffraction gratings are used to
break up light into a spectrum.
reduce diffraction of telescopes.
detect infrared radiation.
increase the resolution of telescopes.
6. The speed of light in glass is
reduced by approximately 60%
reduced by approximately 1%
increased by approximately 50%
the same as in vacuum
7. Diffraction gratings are used for
reducing the diffraction of telescopes.
increasing the angular resolution of telescopes.
analysing the light spectrum.
detecting microwave radiation.
8. Which of the following parameters is the same for all electromagnetic waves propagating in a vacuum?
Speed
Wavelength
Colour
Amplitude
9. Which of the following parameters is the same for all electromagnetic waves propagating in a vacuum?
Speed
Wavelength
Amplitude
Colour
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 amplitude is reduced.
Because the speed of light changes.
Because the frequency increases.
11. A Newtonian telescope has
a diverging secondary mirror.
a flat secondary mirror.
a correction plate.
just the primary mirror.
12. The Hubble telescope was placed in space in order
to improve the magnification.
to not be limited by the Earth’s atmosphere.
to not be limited by the Earth’s horizon.
to be close to the stars.
13. An electromagnetic wave with a wavelength of 600 nm is
visible radiation.
microwave radiation.
ultraviolet radiation.
infrared radiation.
14. Which of the following uses a grazing incidence telescope?
International Space Station.
International Ultraviolet Explorer.
International Space Observatory.
Chandra X-ray satellite.
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.
wavelength of the light.
photoelectric effect.
16. The focal length of an ideal mirror depends on
wavelength of the light.
brightness of the light.
reflectivity of the prism.
photoelectric effect.
17. Light can be described as having a “dual†nature. What does this mean?
Light behaves like a wave and like a particle.
If light moves in one direction, then it moves in the opposite direction also.
Light goes slow and fast.
Light can be expressed as brightness and colour.
18. What is the angular size of the Moon?
0.5 arcminutes
5 degrees
0.5 arcseconds
0.5 degrees
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 remains the same.
The light gathering power increased by a factor of four.
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?
40
160
78
less than 1
22. To detect dim objects a telescope needs
high resolution.
large diameter.
high magnification.
a long tube.
23. A Charge Coupled Device is used in telescopes to
compensate for sagging of the mirror.
improve light gathering.
detect light.
reduce the effect of segmentation of mirrors.
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
infra-red astronomy.
optical astronomy
radio astronomy.
UV astronomy.
26. The LIGO gravitational wave detectors
are bar detectors.
are currently under construction.
have arm lengths of 4 km.
have arm lengths of 600 m.
27. Cerenkov radiation is given off when
a particle is travelling faster than the speed of light in a medium
an electron recombines with an ionised atom
a particle is travelling slower than the speed of light in a medium
an electron is ionised from an atom
28. Why is the colour of the sun during sunset red?
The sun changes its colour in 24 h from blue to red and back to blue.
The 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.
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.
Splitting of the atomic nuclei.
Infra-Red radiation is not absorbed.
30. The ISO satellite is sensitive to
Gamma rays.
UV.
X-rays.
IR.
31. The objective of a telescope is
the part of it which first converges the light.
the object under observation.
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
Dispersion
Refraction
Diffraction
33. How does an infrared telescope make detections?
By monitoring the number of electrons released by incident photons.
By detecting oscillating electric signals generated by incident photons.
By directly detecting the number of incident photons.
By monitoring changes in temperature caused by incident photons.
34. Which of the following processes is responsible for absorption of infrared radiation by the atmosphere?
Conduction in an upper part of the atmosphere.
Interaction of the radiation with the nuclei of atoms in the atmosphere.
The excitation of the vibrational modes of water vapour molecules.
The breaking of chemical bonds in ozone.
35. The twinkling of the stars is due to
absorption.
scattering.
diffusion.
refraction.
36. A Charge Coupled Device is used in telescopes to
improve light gathering.
detect light.
compensate for sagging of the mirror.
reduce the effect of segmentation of mirrors.
37. The Spitzer satellite uses
a prime focus arrangement
a Cassegrain design
a Schmidt-Cassegrain design
a grazing incidence mirror
38. The ISO satellite is sensitive to
IR.
Gamma rays.
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
Neutrino astronomy.
X-Ray astronomy.
Infra-red astronomy.
Radio astronomy.
41. Why are astronomers interested in different parts of the spectrum?
Different parts of the spectrum contain different information.
The results would otherwise interfere destructively.
The different colours are nice.
At some locations at the sky certain detectors do not work.
42. An electromagnetic wave having a wavelength of 550 nm is:
ultra-violet radiation.
gamma radiation.
infrared radiation.
visible radiation.
43. Karl Jansky was the pioneer of
radio astronomy.
optical astronomy.
infra-red astronomy.
UV astronomy.
44. A grazing incidence mirror is used to focus
x-rays.
visible light.
gamma rays.
gravitational waves.
45. Modern observatories are placed on mountains
because it is cheaper to build them on mountains
to get closer to the stars
to reduce the amount of turbulent atmosphere
to be able to observe X-rays
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 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
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 grazing incidence mirrors to focus the high energy gamma rays
has instruments to look at multiple energy bands
uses a large tank of water as a scintillation detector
has imaging CCDis
50. Radio telescopes
do not require a very smooth surface.
need to be cooled.
require a very smooth surface.
operate only at night.
51. LIGO is an acronym for:
Light Ingoing Ground Observations.
Laser Incoming Ground Observation.
Light Incident Gravitational Observation.
Laser Interferometric Gravitational-wave Observatory.
52. 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.
53. Chromatic aberration can occur in a telescope because
the telescope is not stable.
light of different wavelengths are focussed to different positions.
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 million metres per second.
300 thousand metres per second.
30 thousand metres per second.
300 million metres per second.
55. The term 'refraction' is used to describe when light
waves add together to produce brighter light.
changes direction when transmitting through different media.
bends around the edges of objects.
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 an object.
the thickness of the mirror.
the diameter of the mirror.
the distance from the mirror to the focal point.
57. Light can be described as having a "dual" nature. What does this mean?
It travels in two directions at the same time.
It can go fast and slow.
It has brightness and wavelength.
It behaves like a wave and a particle.
58. A Newtonian telescope is
a Cassegrain telescope.
a refracting telescope.
a reflecting telescope.
a prime focus telescope.
59. Astronomers hope to discover gravitational waves by
detecting high-energy gamma rays.
using laser interferometers.
placing radio telescopes in space.
using highly-sensitive CCD sensors.
60. During the day the sky appears blue because
blue light is refracted less 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.
the scattering of blue light is stronger than red light.
61. Atmospheric absorption causes
the scattering of light with large wavelengths.
the stars to twinkle in appearance.
the light from stars to appear stronger than it should.
dimming or extinction of certain wavelengths of light.
62. The resolving power of a radio telescope can be increased by
putting the telescope on a mountain.
making observations during the night.
decreasing the diameter of the primary mirror.
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.
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?
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.
Different parts of the spectrum provide different information.
65. What does the frequency of light mean?
The distance it will travel in 1 second.
The distance from one maximum to another.
How bright the light will be.
The number of times the wave cycle repeats every second.
66. The energy of a photon can be expressed by
E=hc.
E=f/λ.
E=hf.
E=cλ.
67. What is the purpose of the objective lens in a refracting telescope?
To change the speed of the incoming light.
To diffract the incoming light.
To interfere the incoming light.
To focus the incoming light.
68. If a refracting telescope has an objective lens with a focal length of 300cm and has an eyepiece with a focal length of 3cm, the magnification is?
M = 3/300.
M = 300.
M = 1/100.
M = 100.
69. Active optics is used in modern telescopes to
maximise the light gathering power of the telescope.
change the shape of the primary mirror to correct for atmospheric disturbances.
change the detector sensitivity for measuring different wavelengths.
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 refraction, Atmospheric scattering, and Atmospheric absorption.
Atmospheric scattering, Spherical aberration, and Atmospheric refraction.
Atmospheric diffraction, Chromatic aberration, and Atmospheric scattering.
71. For what reason is interferometry used when using multiple telescopes to observe astronomical objects?
To measure different frequencies of light simultaneously.
To increase the resolving power of the detector.
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
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 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.
Red light has a longer wavelength than blue light.
74. A Schmidt-Cassegrain telescope uses which of the following components?
Both lenses and mirrors.
Only lenses.
A diffraction grating.
Only 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
30
1/30
270
76. What are the three important qualities of a telescope?
Diffractive Power, Light Gathering Power, Resolving Power.
Magnification, Diffractive Power, Resolving Power.
Magnification, Diffractive Power, Light Gathering Power.
Magnification, Light Gathering Power, Resolving Power.
77. What causes the twinkling of stars?
Impurities in the lens of the telescope or eye.
Atmospheric Dispersion.
The variation in intensity of light emitted by the star.
Atmospheric refraction.
78. On a cloudless day, why does the sky look blue?
Because the sky reflects the blue colour of the sea.
Because red light is scattered more than blue light.
Because the red light is absorbed by the atmosphere.
Because blue light is scattered more than red light.
79. Grazing incidence mirrors are used to focus light in what type of telescope?
Radio telescopes.
Optical telescopes.
Infra-red telescopes.
X-Ray telescopes.
80. By what method are radio telescopes able to obtain high-resolution images?
By using laser guide adaptive optics.
By having a large field of view.
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?
Gamma rays.
Neutrinos.
Earth-like planets.
Gravitational waves.
82. The James Webb telescope is intended to replace what?
The Infra Red Astronomical Satellite.
The Compton Gamma Ray observatory.
The Chandra observatory.
The Hubble Space telescope.
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 wave, but not a particle.
Light is a particle, but not a wave.
84. Which of the following describes waves whose wavelength is approximately 1 mm?
X-Rays.
Radio waves.
Visible red light.
Microwaves.
85. What is the phenomenon where the velocity of light in a medium depends on its wavelength?
Interference
Dispersion
Diffraction
Refraction
86. Newton's telescope was a
prime focus telescope.
Cassegrain telescope.
refracting telescope.
reflecting telescope.
87. Modern telescopes use CCDs to capture the light. What does the acronym CCD stand for?
Count Collecting Device.
Charge Coupled Diode.
Charge Collecting Diode.
Charge Coupled Device.
88. Ultra-Violet (UV) radiation is emitted by objects of temperature around
1 000 000 K
500 K
10 K
10,000 K
89. The Chandra Observatory is an observatory for
Infra-red astronomy.
Neutrino astronomy.
Radio astronomy.
X-Ray astronomy.
90. Why can X-Rays penetrate inside solids?
They are of very small frequency.
They are very non-reactive.
They are out of phase with ordinary matter.
They have very small wavelengths.
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?
Supernova explosions.
Magellanic clouds.
Pulsars.
Black Hole binary systems.
93. A reflective diffraction grating is separating the light colours and creates a spectrum. What happens if the incoming light is changed from blue to red?
Nothing. Diffraction is wavelength-independent.
The 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 has a constant speed in vacuum.
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.
95. Why are most of the modern telescopes for visible light reflecting telescopes?
Lenses cannot be used for visible light.
Mirrors are easier to make and to mount.
They have no aberration.
It is not possible to melt enough glass to fabricate a large lens.
96. Why are astronomers interested in different parts of the spectrum?
The results would otherwise interfere destructively.
The different colours are nice.
Different parts of the spectrum contain different information.
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 25.
A magnification of 100.
98. 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.
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.
They are based on the photoelectric effect: light kicks out electrons from the material.
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.
It is too dangerous to observe X-rays from astronomical objects.
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?
The moon.
Wavelengths that are shorter than the visible light.
Wavelengths that are in the region of cm.
Radio broadcast of other civilizations in the universe.
102. Gravitational wave astronomy is called a new window to the universe. Why?
Gravitational waves have only a weak interaction with matter. They are carrying information from objects that cannot be observed by studying their emitted electromagnetic radiation.
Gravitational waves will allow a very high resolution when combining a gravitational wave telescope with a CCD.
Gravitational waves can be observed with a simple refractive telescope. Therefore, it would be easier to observe astronomical objects.
They need to be observed from space.
103. Adaptive optics is a technique that reduces the effect of atmospheric turbulence by
varying the mirror reflectivity.
evacuating the telescope tube.
bending the telescope mirror.
adjusting the eyepiece position
104. The angular size of the Moon is
5 degrees.
0.5 degree.
50 degrees.
0.1 degree
105. Which of the following uses a grazing incidence telescope?
Chandra.
Hubble Space telescope.
Spitzer.
International Ultraviolet Explorer.
106. Modern observatories mostly use
photographic film.
observatories at low altitude.
refractive objectives.
CCD detectors.
107. LIGO is an acronym for:
Laser Interferometric Gravitational-wave Observatory.
Light Ingoing Ground Observations.
Laser Incoming Ground Observation.
Light Incident Gravitational Observation.
108. If the diameter of the objective of a telescope is doubled, what happens to its light gathering power? The light gathering power
remains the same.
is increased by a factor of three.
is increased by a factor of two.
is increased by a factor of four.
109. Which of the following processes is responsible for the absorption of Infra-Red radiation?
Infra-Red radiation is not absorbed.
Breaking of the chemical bonds.
Splitting of the atomic nuclei.
Excitation of vibrational modes of molecules.
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:
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
brightness of the light.
speed of the light.
wavelength of the light.
intensity of the light.
113. A Cassegrain telescope
is not a widely used optical design.
is a common optical design used at modern observatories.
has a short focal length.
has a wide field of view.
114. Infra red detectors can work by measuring
radioactive particles.
Cerenkov radiation.
the temperature rise in a material.
energetic charged particles.
115. Wave particle-duality relates to
all of the above.
infra-red radiation.
UV radiation.
visible radiation.
116. The International Ultraviolet Explorer (IUE) experiment
is not a space mission.
is currently in orbit.
is currently being built.
has since finished operation.
117. Scintillation detectors can be made from
stainless steel.
aluminium.
water.
wood.
118. The typical wavelength of an X-ray photon is
1.5 µm.
50 nm.
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
do not require a very smooth surface.
operate only at night.
require a very smooth surface.
need to be cooled.
121. The ISO satellite is sensitive to
IR.
X-rays.
UV.
Gamma rays.
122. A Newtonian telescope utilises a
lens.
corrector plate.
curved secondary mirror.
flat secondary mirror.
123. A prime focus telescope represents a feasible optical configuration
for amateur telescopes.
when interference is used.
when the diameter of the prime mirror is very large.
when the focal length is very long.
124. Which of the following parameters is the same for all electromagnetic waves propagating in a vacuum?
Wavelength
Colour
Speed
Amplitude
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 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.
126. Interference between the light coming from different telescopes is used to
improve the magnification.
improve the resolution.
improve the light gathering.
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 the speed of light changes.
Because the amplitude is reduced.
Because the frequency increases.
Because it interferes with the surface.
128. A Newtonian telescope has
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 longer wavelength.
more photons.
photons with shorter 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 not be limited by the Earth’s atmosphere.
to improve the magnification.
to be close to the stars.
131. An electromagnetic wave with a wavelength of 100 nm is
microwave radiation.
visible radiation.
UV 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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