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 between two consecutive peaks.
The wavelength is the distance travelled by the wave in 1 second.
2. Why does a light ray bend when it crosses the boundary between two different media at an oblique angle?
Because the speed of light changes.
Because the frequency increases.
Because it interferes with the surface.
Because the amplitude is reduced.
3. A Newtonian telescope has
a diverging secondary mirror
a correction plate
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?
Refraction
Interference
Dispersion
Diffraction
5. Diffraction gratings are used to
detect infrared radiation.
increase the resolution of telescopes.
reduce diffraction of telescopes.
break up light into a spectrum.
6. The speed of light in glass is
reduced by approximately 1%
reduced by approximately 60%
increased by approximately 50%
the same as in vacuum
7. Diffraction gratings are used for
analysing the light spectrum.
increasing the angular resolution of telescopes.
reducing the diffraction of telescopes.
detecting microwave radiation.
8. Which of the following parameters is the same for all electromagnetic waves propagating in a vacuum?
Amplitude
Speed
Colour
Wavelength
9. Which of the following parameters is the same for all electromagnetic waves propagating in a vacuum?
Amplitude
Speed
Colour
Wavelength
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
a correction plate.
a flat secondary mirror.
just the primary mirror.
a diverging secondary mirror.
12. 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.
13. An electromagnetic wave with a wavelength of 600 nm is
microwave radiation.
ultraviolet radiation.
visible radiation.
infrared radiation.
14. Which of the following uses a grazing incidence telescope?
International Ultraviolet Explorer.
International Space Station.
Chandra X-ray satellite.
International Space Observatory.
15. The angle through which a ray of light is bent by a glass prism depends on the
reflectivity of the prism.
photoelectric effect.
brightness of the light.
wavelength of the light.
16. The focal length of an ideal mirror depends on
photoelectric effect.
brightness of the light.
reflectivity of the prism.
wavelength of the light.
17. Light can be described as having a “dual†nature. What does this mean?
If light moves in one direction, then it moves in the opposite direction also.
Light can be expressed as brightness and colour.
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 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 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 is increased by a factor of two.
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.
21. For a telescope the objective focal length is 80 cm and the eyepiece focal length is 2 cm, what is the magnification?
160
40
78
less than 1
22. To detect dim objects a telescope needs
high magnification.
large diameter.
a long tube.
high resolution.
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.
remove the effect of Cerenkov radiation.
improve the resolution of objects.
image neutrinos.
25. Karl Jansky was the pioneer of
UV astronomy.
optical astronomy
infra-red astronomy.
radio 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
a particle is travelling slower than the speed of light in a medium
an electron recombines with an ionised atom
a particle is travelling faster than the speed of light in a medium
an electron is ionised from an atom
28. 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 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.
Splitting of the atomic nuclei.
Breaking of the chemical bonds.
30. The ISO satellite is sensitive to
X-rays.
IR.
UV.
Gamma 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?
Diffraction
Interference
Dispersion
Refraction
33. How does an infrared telescope make detections?
By monitoring changes in temperature caused by incident photons.
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.
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.
Interaction of the radiation with the nuclei of atoms in the atmosphere.
The breaking of chemical bonds in ozone.
Conduction in an upper part of the atmosphere.
35. The twinkling of the stars is due to
diffusion.
scattering.
refraction.
absorption.
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 grazing incidence mirror
a Cassegrain design
a Schmidt-Cassegrain design
a prime focus arrangement
38. The ISO satellite is sensitive to
Gamma rays.
UV.
X-rays.
IR.
39. Why are neutrinos so hard to detect in astronomical observatories?
Neutrinos are absorbed in the upper atmosphere.
The neutrinos interact only weakly.
The neutrinos decay before reaching the Earth.
There are no astronomical sources of neutrinos.
40. The Chandra Observatory is an observatory for
X-Ray astronomy.
Infra-red astronomy.
Radio astronomy.
Neutrino 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.
At some locations at the sky certain detectors do not work.
The different colours are nice.
42. An electromagnetic wave having a wavelength of 550 nm is:
visible radiation.
infrared radiation.
ultra-violet radiation.
gamma radiation.
43. Karl Jansky was the pioneer of
infra-red astronomy.
optical astronomy.
radio astronomy.
UV astronomy.
44. A grazing incidence mirror is used to focus
gamma rays.
x-rays.
visible light.
gravitational waves.
45. Modern observatories are placed on mountains
to get closer to the stars
to reduce the amount of turbulent atmosphere
because it is cheaper to build them on mountains
to be able to observe X-rays
46. The Super Kamiokande Neutrino observatory
is located in the Mediterranean sea
is located underground in the USA
is a future planned detector in Japan
is located underground in Japan
47. Cerenkov radiation is given off when
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
48. The typical sensitivity of interferometric gravitational wave detectors is of the order
1 millimeter
1 nanometer
1 attometer
1 micrometer
49. The Compton Gamma Ray Observatory
uses a large tank of water as a scintillation detector
has grazing incidence mirrors to focus the high energy gamma rays
has instruments to look at multiple energy bands
has imaging CCDis
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:
Light Incident Gravitational Observation.
Light Ingoing Ground Observations.
Laser Interferometric Gravitational-wave Observatory.
Laser Incoming Ground 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
the atmosphere is not stable.
light of different wavelengths are focussed to different positions.
the telescope 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 million metres per second.
300 thousand metres per second.
30 thousand metres per second.
55. The term 'refraction' is used to describe when light
bends around the edges of objects.
changes direction when transmitting through different media.
changes frequency when transmitting through different media.
waves add together to produce brighter light.
56. For an astronomical source, the focal length of a mirror is
the distance from the mirror to the focal point.
the distance from the mirror to an object.
the thickness of the mirror.
the diameter of the mirror.
57. Light can be described as having a "dual" nature. What does this mean?
It has brightness and wavelength.
It behaves like a wave and a particle.
It travels in two directions at the same time.
It can go fast and slow.
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 laser interferometers.
placing radio telescopes in space.
detecting high-energy gamma rays.
using highly-sensitive CCD sensors.
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 Sun changes colour over a period of 24 hours.
the atmosphere reflects more red light from the Sun during the day.
61. Atmospheric absorption causes
the scattering of light with large wavelengths.
the stars to twinkle in appearance.
dimming or extinction of certain wavelengths of light.
the light from stars to appear stronger than it should.
62. The resolving power of a radio telescope can be increased by
decreasing the diameter of the primary mirror.
increasing the diameter of the primary mirror.
making observations during the night.
putting the telescope on a mountain.
63. A Schmidt-Cassegrain telescope is one that has?
A corrector plate, a primary mirror and a secondary mirror.
Only mirrors.
Only lenses.
A corrector plate and a primary mirror only.
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 from one maximum to another.
How bright the light will be.
The distance it will travel in 1 second.
The number of times the wave cycle repeats every second.
66. The energy of a photon can be expressed by
E=cλ.
E=hc.
E=hf.
E=f/λ.
67. What is the purpose of the objective lens in a refracting telescope?
To diffract the incoming light.
To focus the incoming light.
To interfere 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 = 1/100.
M = 3/300.
M = 300.
M = 100.
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.
maximise the light gathering power of the telescope.
change the shape of the primary mirror to correct for atmospheric disturbances.
70. The Earth’s atmosphere is responsible for which three phenomena in observational astronomy?
Wave particle duality, Atmospheric scattering, and Atmospheric absorption.
Atmospheric diffraction, Chromatic aberration, and Atmospheric scattering.
Atmospheric scattering, Spherical aberration, and Atmospheric refraction.
Atmospheric refraction, Atmospheric scattering, and Atmospheric absorption.
71. For what reason is interferometry used when using multiple telescopes to observe astronomical objects?
To remove the effect of light pollution.
To reduce the magnification.
To increase the resolving power of the detector.
To measure different frequencies of light simultaneously.
72. Gravitational wave detectors aim to measure the radiation emitted by accelerating masses by
using long-baseline laser interferometers.
using the James Webb Space Telescope.
using multiple radio telescopes around the world.
detecting Cherenkov radiation with photomultiplier tubes.
73. Which of the following statements is false?
Light is a wave of varying electric and magnetic fields.
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.
74. A Schmidt-Cassegrain telescope uses which of the following components?
A diffraction grating.
Both lenses and mirrors.
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?
30
270
60
1/30
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, Resolving Power.
Magnification, Diffractive Power, Light Gathering Power.
77. What causes the twinkling of stars?
Atmospheric refraction.
The variation in intensity of light emitted by the star.
Atmospheric Dispersion.
Impurities in the lens of the telescope or eye.
78. On a cloudless day, why does the sky look blue?
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.
Because red light is scattered more than blue light.
79. Grazing incidence mirrors are used to focus light in what type of telescope?
X-Ray telescopes.
Radio telescopes.
Infra-red 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 computer grinding to construct very smooth mirrors.
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 Compton Gamma Ray observatory.
The Hubble Space telescope.
The Infra Red Astronomical Satellite.
The Chandra observatory.
83. Which of the following is a true statement?
Light is both a wave and a particle.
Light is a particle, but not a wave.
Light is neither a wave nor a particle.
Light is a wave, but not 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?
Refraction
Diffraction
Interference
Dispersion
86. Newton's telescope was a
refracting telescope.
prime focus telescope.
Cassegrain telescope.
reflecting telescope.
87. Modern telescopes use CCDs to capture the light. What does the acronym CCD stand for?
Count Collecting Device.
Charge Collecting Diode.
Charge Coupled 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
X-Ray astronomy.
Radio astronomy.
Infra-red astronomy.
Neutrino astronomy.
90. Why can X-Rays penetrate inside solids?
They have very small wavelengths.
They are of very small frequency.
They are very non-reactive.
They are out of phase with ordinary matter.
91. Why are neutrinos so hard to detect in astronomical observatories?
There are no astronomical sources of neutrinos.
Neutrinos are absorbed in the upper atmosphere.
The neutrinos decay before reaching the Earth.
The neutrinos interact only weakly.
92. Which of the following is NOT a good source of gravitational waves?
Magellanic clouds.
Supernova explosions.
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?
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 has a constant speed in vacuum.
The energy of photons is just dependent on the frequency.
Light travels with different speeds depending on the material.
Light travels always with a constant speed.
95. Why are most of the modern telescopes for visible light reflecting telescopes?
They have no aberration.
Lenses cannot be used for visible light.
It is not possible to melt enough glass to fabricate a large lens.
Mirrors are easier to make and to mount.
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 25.
It is not possible to calculate the magnification with these parameters.
A magnification of 100.
A magnification of 50.
98. 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 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.
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.
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.
100. What is the reason why X-ray telescopes are so much different from telescopes for the visible part of the spectrum?
Materials are nearly transparent in the X-ray band. Standard optical configurations cannot be used.
It is 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.
It is hard to find materials that can be used under X-ray irradiation.
101. What can be observed with radio astronomy?
Radio broadcast of other civilizations in the universe.
Wavelengths that are shorter than the visible light.
The moon.
Wavelengths that are in the region of cm.
102. Gravitational wave astronomy is called a new window to the universe. Why?
Gravitational waves will allow a very high resolution when combining a gravitational wave telescope with a CCD.
They need to be observed from space.
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.
103. Adaptive optics is a technique that reduces the effect of atmospheric turbulence by
bending the telescope mirror.
varying the mirror reflectivity.
adjusting the eyepiece position
evacuating the telescope tube.
104. The angular size of the Moon is
0.5 degree.
5 degrees.
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
refractive objectives.
observatories at low altitude.
photographic film.
CCD detectors.
107. LIGO is an acronym for:
Laser Incoming Ground Observation.
Laser Interferometric Gravitational-wave Observatory.
Light Ingoing Ground Observations.
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
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.
Breaking of the chemical bonds.
Excitation of vibrational modes of molecules.
Splitting of the atomic nuclei.
110. Long Baseline Interferometry is a technique often used in radio astronomy to
improve the resolution of objects.
remove the effect of Cerenkov radiation.
image neutrinos.
reduce the effect of light pollution in urban skies.
111. An electromagnetic wave having a wavelength of 550 nm is:
visible radiation.
ultra-violet radiation.
gamma radiation.
infrared 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.
brightness of the light.
wavelength of the light.
113. A Cassegrain telescope
has a short focal length.
has a wide field of view.
is not a widely used optical design.
is a common optical design used at modern observatories.
114. Infra red detectors can work by measuring
the temperature rise in a material.
Cerenkov radiation.
radioactive particles.
energetic charged particles.
115. Wave particle-duality relates to
infra-red radiation.
UV radiation.
all of the above.
visible radiation.
116. The International Ultraviolet Explorer (IUE) experiment
is currently being built.
is not a space mission.
has since finished operation.
is currently in orbit.
117. Scintillation detectors can be made from
wood.
water.
stainless steel.
aluminium.
118. The typical wavelength of an X-ray photon is
0.1 nm.
50 nm.
1.5 µm.
600 nm.
119. A light wave with large amplitude has a
high frequency.
high brightness.
long wavelength.
low brightness.
120. Radio telescopes
need to be cooled.
do not require a very smooth surface.
operate only at night.
require a very smooth surface.
121. The ISO satellite is sensitive to
Gamma rays.
IR.
UV.
X-rays.
122. A Newtonian telescope utilises a
lens.
curved secondary mirror.
corrector plate.
flat secondary mirror.
123. A prime focus telescope represents a feasible optical configuration
when the focal length is very long.
for amateur telescopes.
when the diameter of the prime mirror is very large.
when interference is used.
124. Which of the following parameters is the same for all electromagnetic waves propagating in a vacuum?
Amplitude
Wavelength
Colour
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 gathering.
improve the magnification.
improve the light spectrum.
improve the resolution.
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
a diverging secondary mirror
a correction plate
just the primary mirror
a flat 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 atmosphere.
to improve the magnification.
to not be limited by the Earth’s horizon.
to be close to the stars.
131. An electromagnetic wave with a wavelength of 100 nm is
IR radiation.
microwave radiation.
visible radiation.
UV radiation.
132. The angular size of the Moon is
1.8 degrees
1 800 arcminutes
1 800 arcseconds
18 degrees
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