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 two consecutive peaks.
The wavelength is the distance travelled by the wave in 1 second.
The wavelength is the distance between a trough and a peak.
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 frequency increases.
Because the speed of light changes.
3. A Newtonian telescope has
just the primary mirror
a flat secondary mirror
a diverging secondary mirror
a correction plate
4. As light passes from one medium to another, its direction of travel changes. What is the name of this effect?
Interference
Diffraction
Refraction
Dispersion
5. Diffraction gratings are used to
increase the resolution of telescopes.
break up light into a spectrum.
detect infrared radiation.
reduce diffraction of telescopes.
6. The speed of light in glass is
the same as in vacuum
increased by approximately 50%
reduced by approximately 1%
reduced by approximately 60%
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?
Colour
Speed
Wavelength
Amplitude
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 it interferes with the surface.
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 horizon.
to not be limited by the Earth’s atmosphere.
to be close to the stars.
13. An electromagnetic wave with a wavelength of 600 nm is
infrared radiation.
microwave radiation.
ultraviolet radiation.
visible 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
wavelength of the light.
photoelectric effect.
brightness of the light.
reflectivity of the prism.
16. The focal length of an ideal mirror depends on
reflectivity of the prism.
photoelectric effect.
wavelength of the light.
brightness of the light.
17. Light can be described as having a “dual†nature. What does this mean?
Light goes slow and fast.
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.
18. What is the angular size of the Moon?
0.5 degrees
0.5 arcminutes
0.5 arcseconds
5 degrees
19. Which of the following space-based telescopes detected water in the Orion nebula?
The International Space Observatory (ISO)
Chandra
Hubble
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 increased by a factor of two.
The light gathering power is decreased by a factor of four.
The light gathering power increased 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
78
160
less than 1
22. To detect dim objects a telescope needs
high resolution.
high magnification.
large diameter.
a long tube.
23. A Charge Coupled Device is used in telescopes to
improve light gathering.
compensate for sagging of the mirror.
reduce the effect of segmentation of mirrors.
detect light.
24. 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.
25. Karl Jansky was the pioneer of
optical astronomy
infra-red astronomy.
radio astronomy.
UV astronomy.
26. The LIGO gravitational wave detectors
are currently under construction.
have arm lengths of 4 km.
are bar detectors.
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
a particle is travelling slower than the speed of light in a medium
an electron recombines with an ionised atom
an electron is ionised from an atom
28. Why is the colour of the sun during sunset red?
The refraction of light is different. Blue light is more strongly refracted.
The scattering of blue light is stronger than red light.
The sun changes its colour in 24 h from blue to red and back to blue.
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?
Infra-Red radiation is not absorbed.
Breaking of the chemical bonds.
Excitation of vibrational modes of molecules.
Splitting of the atomic nuclei.
30. The ISO satellite is sensitive to
UV.
IR.
Gamma rays.
X-rays.
31. The objective of a telescope is
the part of it which first converges the light.
the adaptor between the telescope and the human eye.
the reason why that telescope has been buil
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
Interference
Diffraction
Refraction
33. How does an infrared telescope make detections?
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.
By directly detecting the number of 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
refraction.
absorption.
scattering.
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 Schmidt-Cassegrain design
a grazing incidence mirror
a prime focus arrangement
a Cassegrain design
38. The ISO satellite is sensitive to
Gamma rays.
X-rays.
UV.
IR.
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 interact only weakly.
The neutrinos decay before reaching the Earth.
40. The Chandra Observatory is an observatory for
Infra-red astronomy.
X-Ray astronomy.
Neutrino astronomy.
Radio astronomy.
41. Why are astronomers interested in different parts of the spectrum?
The results would otherwise interfere destructively.
The different colours are nice.
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.
ultra-violet radiation.
infrared radiation.
gamma radiation.
43. Karl Jansky was the pioneer of
infra-red astronomy.
radio astronomy.
UV astronomy.
optical 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 be able to observe X-rays
to get closer to the stars
because it is cheaper to build them on mountains
to reduce the amount of turbulent atmosphere
46. The Super Kamiokande Neutrino observatory
is located underground in Japan
is located in the Mediterranean sea
is located underground in the USA
is a future planned detector in Japan
47. Cerenkov radiation is given off when
an electron 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
an electron recombines with an ionised atom
48. The typical sensitivity of interferometric gravitational wave detectors is of the order
1 attometer
1 micrometer
1 nanometer
1 millimeter
49. The Compton Gamma Ray Observatory
has instruments to look at multiple energy bands
uses a large tank of water as a scintillation detector
has imaging CCDis
has grazing incidence mirrors to focus the high energy gamma rays
50. Radio telescopes
operate only at night.
do not require a very smooth surface.
require a very smooth surface.
need to be cooled.
51. LIGO is an acronym for:
Laser Interferometric Gravitational-wave Observatory.
Light Incident Gravitational Observation.
Light Ingoing Ground Observations.
Laser Incoming Ground Observation.
52. 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.
image neutrinos.
remove the effect of Cerenkov radiation.
53. Chromatic aberration can occur in a telescope because
the atmosphere is not stable.
light of different wavelengths are reflected to different positions.
light of different wavelengths are focussed to different positions.
the telescope is not stable.
54. The speed of light in a vacuum is approximately
300 million metres per second.
300 thousand metres per second.
30 thousand metres per second.
30 million metres per second.
55. The term 'refraction' is used to describe when light
bends around the edges of objects.
waves add together to produce brighter light.
changes frequency when transmitting through different media.
changes direction when transmitting through different media.
56. For an astronomical source, the focal length of a mirror is
the distance from the mirror to the focal point.
the thickness of the mirror.
the diameter of the mirror.
the distance from the mirror to an object.
57. Light can be described as having a "dual" nature. What does this mean?
It has brightness and wavelength.
It travels in two directions at the same time.
It can go fast and slow.
It behaves like a wave and a particle.
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.
placing radio telescopes in space.
using highly-sensitive CCD sensors.
detecting high-energy gamma rays.
60. During the day the sky appears blue because
the scattering of blue light is stronger 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.
blue light is refracted less than red light.
61. Atmospheric absorption causes
the stars to twinkle in appearance.
the scattering of light with large wavelengths.
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.
increasing the diameter of the primary mirror.
decreasing the diameter of the primary mirror.
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?
Because in vacuum light travels at different speeds at different wavelengths.
Stars emit mainly ultraviolet radiation.
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?
The distance from one maximum to another.
How bright the light will be.
The number of times the wave cycle repeats every second.
The distance it will travel in 1 second.
66. The energy of a photon can be expressed by
E=hf.
E=f/λ.
E=hc.
E=cλ.
67. What is the purpose of the objective lens in a refracting telescope?
To change the speed of the incoming light.
To focus the incoming light.
To interfere the incoming light.
To diffract 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 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.
change the detector sensitivity for measuring different wavelengths.
70. The Earth’s atmosphere is responsible for which three phenomena in observational astronomy?
Atmospheric scattering, Spherical aberration, and Atmospheric refraction.
Atmospheric refraction, Atmospheric scattering, and Atmospheric absorption.
Atmospheric diffraction, Chromatic aberration, and Atmospheric scattering.
Wave particle duality, Atmospheric scattering, and Atmospheric absorption.
71. For what reason is interferometry used when using multiple telescopes to observe astronomical objects?
To increase the resolving power of the detector.
To reduce the magnification.
To measure different frequencies of light simultaneously.
To remove the effect of light pollution.
72. Gravitational wave detectors aim to measure the radiation emitted by accelerating masses by
using long-baseline laser interferometers.
detecting Cherenkov radiation with photomultiplier tubes.
using multiple radio telescopes around the world.
using the James Webb Space Telescope.
73. Which of the following statements is false?
Light travels faster in glass than in a vacuum.
Red light has a longer wavelength than blue light.
Light is both a wave and a particle.
Light is a wave of varying electric and magnetic fields.
74. A Schmidt-Cassegrain telescope uses which of the following components?
Only mirrors.
Only lenses.
A diffraction grating.
Both lenses and mirrors.
75. If a telescope has an objective with a focal length of 90 cm and an eyepiece with focal length of 3 cm, what is the magnification of the telescope?
60
1/30
270
30
76. What are the three important qualities of a telescope?
Magnification, 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.
Impurities in the lens of the telescope or eye.
The variation in intensity of light emitted by the star.
Atmospheric Dispersion.
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 red light is scattered more than blue light.
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 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.
By using laser guide adaptive optics.
81. Super-Kamiokande is an experiment designed to detect what?
Earth-like planets.
Gamma rays.
Gravitational waves.
Neutrinos.
82. The James Webb telescope is intended to replace what?
The Chandra observatory.
The Infra Red Astronomical Satellite.
The Compton Gamma Ray observatory.
The Hubble Space telescope.
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?
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?
Diffraction
Interference
Refraction
Dispersion
86. Newton's telescope was a
reflecting telescope.
refracting telescope.
Cassegrain 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 K
10,000 K
500 K
89. The Chandra Observatory is an observatory for
Radio astronomy.
Neutrino astronomy.
X-Ray astronomy.
Infra-red astronomy.
90. Why can X-Rays penetrate inside solids?
They are very non-reactive.
They are out of phase with ordinary matter.
They are of very small frequency.
They have very small wavelengths.
91. Why are neutrinos so hard to detect in astronomical observatories?
The neutrinos decay before reaching the Earth.
Neutrinos are absorbed in the upper atmosphere.
There are no astronomical sources of neutrinos.
The neutrinos interact only weakly.
92. Which of the following is NOT a good source of gravitational waves?
Black Hole binary systems.
Supernova explosions.
Pulsars.
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 angle between the diffraction orders becomes larger.
Nothing. Diffraction is wavelength-independent.
The outcoming light stays blue.
The red light is transmitted through the grating because only blue light is scattered.
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?
Mirrors are easier to make and to mount.
It is not possible to melt enough glass to fabricate a large lens.
They have no aberration.
Lenses cannot be used for visible light.
96. Why are astronomers interested in different parts of the spectrum?
At some locations at the sky certain detectors do not work.
The results would otherwise interfere destructively.
The different colours are nice.
Different parts of the spectrum contain different information.
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 100.
A magnification of 50.
It is not possible to calculate the magnification with these parameters.
A magnification of 25.
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 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.
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 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.
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 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.
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.
101. What can be observed with radio astronomy?
Radio broadcast of other civilizations in the universe.
Wavelengths that are in the region of cm.
The moon.
Wavelengths that are shorter than the visible light.
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
adjusting the eyepiece position
varying the mirror reflectivity.
bending the telescope mirror.
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?
Spitzer.
International Ultraviolet Explorer.
Hubble Space telescope.
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.
Light Ingoing Ground Observations.
Laser Interferometric Gravitational-wave Observatory.
Laser Incoming Ground 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 three.
is increased by a factor of four.
is increased by a factor of two.
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
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
brightness of the light.
wavelength of the light.
speed of the light.
intensity of the light.
113. A Cassegrain telescope
has a short focal length.
is a common optical design used at modern observatories.
is not a widely used optical design.
has a wide field of view.
114. Infra red detectors can work by measuring
Cerenkov radiation.
energetic charged particles.
radioactive particles.
the temperature rise in a material.
115. Wave particle-duality relates to
all of the above.
UV radiation.
visible radiation.
infra-red radiation.
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
aluminium.
wood.
stainless steel.
water.
118. The typical wavelength of an X-ray photon is
50 nm.
600 nm.
1.5 µm.
0.1 nm.
119. A light wave with large amplitude has a
high frequency.
low brightness.
long wavelength.
high brightness.
120. Radio telescopes
operate only at night.
require a very smooth surface.
need to be cooled.
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
corrector plate.
curved secondary mirror.
flat secondary mirror.
lens.
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?
Colour
Wavelength
Speed
Amplitude
125. Which of the following statements correctly describes the wavelength of an electromagnetic wave?
The wavelength is the distance between two consecutive peaks.
The wavelength is the distance travelled by the wave in 1 second.
The wavelength is the distance travelled by the wave in a short time.
The wavelength is the distance between a trough and a peak.
126. Interference between the light coming from different telescopes is used to
improve the magnification.
improve the resolution.
improve the light spectrum.
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 speed of light changes.
Because the frequency increases.
Because the amplitude is reduced.
128. A Newtonian telescope has
just the primary mirror
a correction plate
a diverging secondary mirror
a flat secondary mirror
129. With respect to a dim light, a bright light emits
more photons.
photons with shorter wavelength.
photons with longer 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 not be limited by the Earth’s horizon.
to improve the magnification.
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
18 degrees
1 800 arcseconds
1 800 arcminutes
1.8 degrees
133. Hello
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