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 a short time.
The wavelength is the distance between a trough and a peak.
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 it interferes with the surface.
Because the amplitude is reduced.
Because the speed of light changes.
Because the frequency increases.
3. A Newtonian telescope has
a flat secondary mirror
a correction plate
just the primary mirror
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?
Diffraction
Refraction
Dispersion
Interference
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 60%
the same as in vacuum
increased by approximately 50%
reduced by approximately 1%
7. Diffraction gratings are used for
detecting microwave radiation.
reducing the diffraction of telescopes.
analysing the light spectrum.
increasing the angular resolution of telescopes.
8. Which of the following parameters is the same for all electromagnetic waves propagating in a vacuum?
Amplitude
Colour
Wavelength
Speed
9. Which of the following parameters is the same for all electromagnetic waves propagating in a vacuum?
Speed
Wavelength
Colour
Amplitude
10. Why does a light ray bend when it crosses the boundary between two different media at an oblique angle?
Because it interferes with the surface.
Because the frequency increases.
Because the amplitude is reduced.
Because the speed of light changes.
11. A Newtonian telescope has
a correction plate.
a flat secondary mirror.
just the primary 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 improve the magnification.
to be close to the stars.
to not be limited by the Earth’s atmosphere.
13. An electromagnetic wave with a wavelength of 600 nm is
ultraviolet radiation.
microwave radiation.
infrared radiation.
visible radiation.
14. Which of the following uses a grazing incidence telescope?
International Ultraviolet Explorer.
Chandra X-ray satellite.
International Space Station.
International Space Observatory.
15. The angle through which a ray of light is bent by a glass prism depends on the
wavelength of the light.
photoelectric effect.
brightness of the light.
reflectivity of the prism.
16. The focal length of an ideal mirror depends on
brightness of the light.
reflectivity of the prism.
photoelectric effect.
wavelength of the light.
17. Light can be described as having a “dual†nature. What does this mean?
Light can be expressed as brightness and colour.
Light behaves like a wave and like a particle.
Light goes slow and fast.
If light moves in one direction, then it moves in the opposite direction also.
18. What is the angular size of the Moon?
0.5 arcseconds
5 degrees
0.5 arcminutes
0.5 degrees
19. Which of the following space-based telescopes detected water in the Orion nebula?
Hubble
The International Space Observatory (ISO)
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 is decreased by a factor of four.
The light gathering power increased 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
78
less than 1
160
22. To detect dim objects a telescope needs
large diameter.
high resolution.
a long tube.
high magnification.
23. A Charge Coupled Device is used in telescopes to
compensate for sagging of the mirror.
reduce the effect of segmentation of mirrors.
detect light.
improve light gathering.
24. Long Baseline Interferometry is a technique often used in radio astronomy to
image neutrinos.
remove the effect of Cerenkov radiation.
improve the resolution of objects.
reduce the effect of light pollution in urban skies.
25. Karl Jansky was the pioneer of
radio astronomy.
optical astronomy
UV astronomy.
infra-red astronomy.
26. The LIGO gravitational wave detectors
have arm lengths of 600 m.
have arm lengths of 4 km.
are currently under construction.
are bar detectors.
27. Cerenkov radiation is given off when
an electron is ionised from an atom
an electron recombines with an ionised 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 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.
IR.
X-rays.
31. The objective of a telescope is
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.
the object under observation.
32. As light passes from one medium to another, its direction of travel changes. What is the name of this effect?
Dispersion
Diffraction
Interference
Refraction
33. How does an infrared telescope make detections?
By monitoring changes in temperature caused by incident photons.
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.
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.
Conduction in an upper part of the atmosphere.
The breaking of chemical bonds in ozone.
The excitation of the vibrational modes of water vapour molecules.
35. The twinkling of the stars is due to
scattering.
absorption.
diffusion.
refraction.
36. A Charge Coupled Device is used in telescopes to
reduce the effect of segmentation of mirrors.
detect light.
compensate for sagging of the mirror.
improve light gathering.
37. The Spitzer satellite uses
a Schmidt-Cassegrain design
a grazing incidence mirror
a prime focus arrangement
a Cassegrain design
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.
Neutrinos are absorbed in the upper atmosphere.
The neutrinos decay before reaching the Earth.
The neutrinos interact only weakly.
40. The Chandra Observatory is an observatory for
Neutrino astronomy.
Radio astronomy.
X-Ray astronomy.
Infra-red astronomy.
41. Why are astronomers interested in different parts of the spectrum?
The different colours are nice.
The results would otherwise interfere destructively.
At some locations at the sky certain detectors do not work.
Different parts of the spectrum contain different information.
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
UV astronomy.
optical astronomy.
infra-red astronomy.
radio astronomy.
44. A grazing incidence mirror is used to focus
gamma rays.
x-rays.
gravitational waves.
visible light.
45. Modern observatories are placed on mountains
to reduce the amount of turbulent atmosphere
because it is cheaper to build them on mountains
to be able to observe X-rays
to get closer to the stars
46. The Super Kamiokande Neutrino observatory
is located underground in the USA
is located underground in Japan
is located in the Mediterranean sea
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 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
48. The typical sensitivity of interferometric gravitational wave detectors is of the order
1 micrometer
1 millimeter
1 attometer
1 nanometer
49. The Compton Gamma Ray Observatory
has instruments to look at multiple energy bands
has imaging CCDis
has grazing incidence mirrors to focus the high energy gamma rays
uses a large tank of water as a scintillation detector
50. Radio telescopes
operate only at night.
do not require a very smooth surface.
need to be cooled.
require a very smooth surface.
51. LIGO is an acronym for:
Light Incident Gravitational Observation.
Laser Incoming Ground Observation.
Light Ingoing Ground Observations.
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.
image neutrinos.
improve the resolution of objects.
53. Chromatic aberration can occur in a telescope because
the telescope is not stable.
the atmosphere is not stable.
light of different wavelengths are focussed to different positions.
light of different wavelengths are reflected to different positions.
54. The speed of light in a vacuum is approximately
300 thousand metres per second.
30 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.
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 thickness of the mirror.
the diameter of the mirror.
the distance from the mirror to the focal point.
the distance from the mirror to an object.
57. Light can be described as having a "dual" nature. What does this mean?
It can go fast and slow.
It travels in two directions at the same time.
It behaves like a wave and a particle.
It has brightness and wavelength.
58. A Newtonian telescope is
a Cassegrain telescope.
a refracting telescope.
a prime focus telescope.
a reflecting 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 Sun changes colour over a period of 24 hours.
blue light is refracted less than red light.
the scattering of blue light is stronger than red light.
the atmosphere reflects more red light from the Sun during the day.
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
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.
A corrector plate and a primary mirror only.
Only lenses.
64. Why are astronomers interested in measuring light at different parts of the electromagnetic spectrum?
Because visible light is hard to detect on Earth.
Stars emit mainly ultraviolet radiation.
Different parts of the spectrum provide different information.
Because in vacuum light travels at different speeds at different wavelengths.
65. What does the frequency of light mean?
The distance it will travel in 1 second.
The number of times the wave cycle repeats every 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=hc.
E=f/λ.
E=hf.
E=cλ.
67. What is the purpose of the objective lens in a refracting telescope?
To focus the incoming light.
To diffract 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 = 100.
M = 1/100.
M = 3/300.
M = 300.
69. Active optics is used in modern telescopes to
maximise the light gathering power of the telescope.
change the focal length of the primary mirror for different astronomical objects.
change the detector sensitivity for measuring different wavelengths.
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 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 reduce the magnification.
To remove the effect of light pollution.
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
detecting Cherenkov radiation with photomultiplier tubes.
using long-baseline laser interferometers.
using the James Webb Space Telescope.
using multiple radio telescopes around the world.
73. Which of the following statements is false?
Light is both a wave and a particle.
Light travels faster in glass than in a vacuum.
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?
270
30
1/30
60
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?
Atmospheric Dispersion.
The variation in intensity of light emitted by the star.
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 the red light is absorbed by the atmosphere.
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?
Radio telescopes.
Infra-red telescopes.
Optical telescopes.
X-Ray telescopes.
80. By what method are radio telescopes able to obtain high-resolution images?
By using laser guide adaptive optics.
By using computer grinding to construct very smooth mirrors.
By having a large field of view.
By using the interference of signals from many radio telescopes.
81. Super-Kamiokande is an experiment designed to detect what?
Neutrinos.
Gravitational waves.
Earth-like planets.
Gamma rays.
82. The James Webb telescope is intended to replace what?
The Chandra observatory.
The Hubble Space telescope.
The Infra Red Astronomical Satellite.
The Compton Gamma Ray observatory.
83. Which of the following is a true statement?
Light is a particle, but not a wave.
Light is both a wave and a particle.
Light is a wave, but not a particle.
Light is neither a wave nor a particle.
84. Which of the following describes waves whose wavelength is approximately 1 mm?
Radio waves.
Microwaves.
Visible red light.
X-Rays.
85. What is the phenomenon where the velocity of light in a medium depends on its wavelength?
Dispersion
Refraction
Interference
Diffraction
86. Newton's telescope was a
refracting telescope.
reflecting telescope.
prime focus telescope.
Cassegrain telescope.
87. Modern telescopes use CCDs to capture the light. What does the acronym CCD stand for?
Charge Coupled Device.
Charge Collecting Diode.
Charge Coupled Diode.
Count Collecting Device.
88. Ultra-Violet (UV) radiation is emitted by objects of temperature around
10,000 K
500 K
1 000 000 K
10 K
89. The Chandra Observatory is an observatory for
Infra-red astronomy.
Neutrino astronomy.
X-Ray astronomy.
Radio astronomy.
90. Why can X-Rays penetrate inside solids?
They are of very small frequency.
They are out of phase with ordinary matter.
They are very non-reactive.
They have very small wavelengths.
91. Why are neutrinos so hard to detect in astronomical observatories?
The neutrinos decay before reaching the Earth.
The neutrinos interact only weakly.
There are no astronomical sources of neutrinos.
Neutrinos are absorbed in the upper atmosphere.
92. Which of the following is NOT a good source of gravitational waves?
Pulsars.
Supernova explosions.
Black Hole binary systems.
Magellanic clouds.
93. A reflective diffraction grating is separating the light colours and creates a spectrum. What happens if the incoming light is changed from blue to red?
The red light is transmitted through the grating because only blue light is scattered.
The angle between the diffraction orders becomes larger.
Nothing. Diffraction is wavelength-independent.
The outcoming light stays blue.
94. Which statement is wrong?
Light travels with different speeds depending on the material.
Light travels always with a constant speed.
The energy of photons is just dependent on the frequency.
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.
They have no aberration.
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?
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 25.
A magnification of 50.
A magnification of 100.
98. Why is the colour of the sun during sunset red?
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.
The refraction of light is different. Blue light is more strongly refracted.
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.
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.
100. What is the reason why X-ray telescopes are so much different from telescopes for the visible part of the spectrum?
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.
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.
101. What can be observed with radio astronomy?
Wavelengths that are shorter than the visible light.
Radio broadcast of other civilizations in the universe.
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.
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 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
bending the telescope mirror.
adjusting the eyepiece position
varying the mirror reflectivity.
evacuating the telescope tube.
104. The angular size of the Moon is
50 degrees.
5 degrees.
0.5 degree.
0.1 degree
105. Which of the following uses a grazing incidence telescope?
Hubble Space telescope.
Chandra.
International Ultraviolet Explorer.
Spitzer.
106. Modern observatories mostly use
refractive objectives.
observatories at low altitude.
photographic film.
CCD detectors.
107. LIGO is an acronym for:
Laser Interferometric Gravitational-wave Observatory.
Laser Incoming Ground Observation.
Light Incident Gravitational Observation.
Light Ingoing Ground Observations.
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 three.
is increased by a factor of four.
remains the same.
is increased by a factor of two.
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
improve the resolution of objects.
image neutrinos.
reduce the effect of light pollution in urban skies.
remove the effect of Cerenkov radiation.
111. An electromagnetic wave having a wavelength of 550 nm is:
visible radiation.
infrared radiation.
gamma 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.
intensity of the light.
wavelength 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
Cerenkov radiation.
the temperature rise in a material.
radioactive particles.
energetic charged particles.
115. Wave particle-duality relates to
visible radiation.
UV radiation.
infra-red radiation.
all of the above.
116. The International Ultraviolet Explorer (IUE) experiment
has since finished operation.
is currently being built.
is not a space mission.
is currently in orbit.
117. Scintillation detectors can be made from
stainless steel.
wood.
aluminium.
water.
118. The typical wavelength of an X-ray photon is
1.5 µm.
0.1 nm.
50 nm.
600 nm.
119. A light wave with large amplitude has a
high frequency.
low brightness.
long wavelength.
high brightness.
120. Radio telescopes
do not require a very smooth surface.
need to be cooled.
operate only at night.
require a very smooth surface.
121. The ISO satellite is sensitive to
IR.
Gamma rays.
X-rays.
UV.
122. A Newtonian telescope utilises a
lens.
flat secondary mirror.
corrector plate.
curved 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?
Speed
Colour
Amplitude
Wavelength
125. 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.
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 the frequency increases.
Because it interferes with the surface.
Because the speed of light changes.
Because the amplitude is reduced.
128. A Newtonian telescope has
just the primary mirror
a flat secondary mirror
a correction plate
a diverging secondary mirror
129. With respect to a dim light, a bright light emits
more photons.
photons with higher amplitude.
photons with shorter wavelength.
photons with longer wavelength.
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 improve the magnification.
to not be limited by the Earth’s atmosphere.
131. An electromagnetic wave with a wavelength of 100 nm is
visible radiation.
UV radiation.
IR radiation.
microwave radiation.
132. The angular size of the Moon is
18 degrees
1 800 arcminutes
1.8 degrees
1 800 arcseconds
133. Hello
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