telescopes are placed in space to view distant galaxies primarily
A to get closer to the observed objects
B to avoid the absorption of the light or other radiations in the atmosphere of Earth
C to avoid having to steer the telescope against the Earth's motion
D to avoid the light pollution from the Earth's populated areas
what is the most important function of a telescope?
A magnification
B resolution
C light collection
D none of the above
the most serious disadvantage of refracting telescopes is
A their extreme expense
B their awkward size
C the inconvenient location of the focused image
D distortion of the image due to sagging and bending
astronomers wish to build larger and larger telescopes because larger telescopes
A allow fainter objects to be seen.
B allow more detail in the image to be seen or photographed.
C produce greater magnification of the image.
D allow more wavelengths to be studied.
E both (a) and (b).
the primary purpose of a parabolic mirror in a reflector is
A to correct for spherical aberration
B to deflect light to a high-power eyepiece
C to correct for chromatic aberration
D to act as an objective, gathering light
telescopes in satellites are currently used primarily to observe
A objects too faint to observe with ground based telescopes
B types of light waves which are almost totally absorbed by the Earth's atmosphere
C objects obscured by terrestrial pollution
D objects visible only during daytime on the Earth
the purpose of the prism in a spectroscope is to
A eliminate chromatic aberration
B focus the light
C separate the colors
D balance the spectroscope
the coude focus is used because:
A it focuses light at a fixed point
B it is easy to make
C it is very efficient
D it is easy on the astronomer
most large observatories are built
A close to populous areas for easy access
B on desert mountains for clear weather and dark skies
C in remote areas to keep tourists away
D no choice
the greater the _____ the greater the light gathering power
A objective focal length
B resolution
C objective diameter
D magnification
the advantage to using high magnification at the telescope is
A greater light-collecting ability
B to allow the eye to see greater detail
C better resolution
D less twinkling of the image
below are the main functions of a telescope. which one is the most important?
A magnification
B gathering light.
C resolution.
D none; all are equally important.
the primary mirror of a reflecting telescope is used to
A reflect light outside the tube for viewing
B gather and focus the light
C aid in pointing the telescope
D support auxiliary equipment
the bending of light rays when they enter a piece of glass is called
A reflection
B refraction
C aberration
D cassegraining
radio telescopes are expensive because
A sophisticated electronic equipment is needed
B remote locations are needed
C large apertures are needed
D no choice
which of the following features determines the resolving power of a telescope?
A the diameter of the objective.
B the focal length of the objective.
C the focal length of the eyepiece.
D two of the above.
the purpose of a telescope objective is to
A disperse white light into its component colors
B magnify the size of the image
C collect light and form an image
D measure the amount of energy carried by electromagnetic waves
large refractors are no longer made because
A it is difficult to make a large lens without optical defects and weight problems
B it is much easier to make many smaller lens and use them in a multi-lens telescope
C it is harder to make the objective mirror in the refractor than the main reflecting mirror in a refractor
D the metal mirrors used in most reflectors are cheaper than glass lens
the principle optical component of a refracting telescope is a
A lens
B mirror
C prism
D tube
interferometry is used to increase
A magnifying power.
B resolving power.
C radiation-gathering power.
D all of the above.
E none of the above.
the part of the spectroscope which breaks white light into the various colors is the
A telescope
B prism
C collimator
D photographic film.
the magnification of a given telescope can be changed
A by putting a shade on the objective to change its effective diameter.
B only by changing the objective lens or mirror.
C by reducing resolving power.
D by using spectroscopy selectively.
E by changing eyepieces.
one axis of an equatorial mount
A points to Vega
B points to the north geographic pole of the Earth
C points to Polaris
D no choice
large telescopes are reflecting rather than refracting because
A the light gathering power of mirrors is greater than that of lenses
B lenses more accurately bend light rays to the focus
C mirrors are easier to support than lenses
D no choice
astronomers have constructed radio interferometers mainly to
A spend lots of money.
B increase the resolving power.
C increase the light-gathering power.
D increase the magnification.
which of the following features determines the light-gathering power of a telescope?
A the diameter of the objective.
B the focal length of the objective.
C the focal length of the eyepiece.
D two of the above.
the main function of a telescope is generally to
A magnify star images
B separate light into its spectrum
C help us see radiation that cannot get through clouds
D collect more radiation from faint objects
the main function of a telescope objective is to
A decrease chromatic aberration.
B collect light.
C disperse light.
D magnify images.
E none of the above.
refraction is
A the change in direction of light when it bounces off a smooth surface
B the change in the color of light when it enters a transparent but colored material such as glass
C the bending of light as it enters a transparent material
D the bending of light round the sharp edge of the obstacle
when you look at a star through a large telescope, you see
A a uniform disk
B a point of light
C a disk with surface features
D a spectrum
many large optical telescopes are adversely affected by
A light pollution
B sound pollution
C small but frequent Earthquakes
D insufficient number of astronomers to operate them
most reflecting telescopes have a secondary mirror that is used
A when the primary is worn out
B to gather additional light
C to provide a second, reference beam of light
D to reflect the image outside the tube for convenient viewing.
what does a refracting telescope use to gather the light of a star
A an electronic device
B a lens
C a mirror
D a tube?
mountain top observatories provide better
A atmospheric seeing
B dark sky conditions
C air transparency
D all of the above
seeing refers to
A the lack of clouds in the atmosphere
B how far a telescope can see
C the faintest object observable through a telescope
D the smearing of an image caused by atmospheric motions
fixed radio telescopes are common because
A radio astronomers are too lazy to build movable ones
B they need to be very large to obtain good resolution
C only limited areas of the sky are of interest to radio astronomers
D no choice
which of the following powers of a telescope does not depend directly on the diameter of the objective lens or mirror?
A magnifying power
B light gathering power
C resolving power
D none of the above
Karl Jansky is the inventor of
A the achromatic lens
B the schmidt telescope
C the radio telescope
D the equatorial mount
large astronomical telescopes are desirable because they allow astronomers to
A obtain larger images of stars
B obtain brighter images of stars
C see more of the sky at one time
D spend more money
what is the primary reason that astronomers want to orbit a large optical telescope above the Earth's atmosphere?
A it is cheaper than a ground-based telescope.
B better resolving power.
C availability of a wider range of the spectrum.
D (a) and (b)
E (b) and (c)
the most important property of a telescope for astronomers is its power to
A magnify
B resolve fine detail
C gather light
D focus many stars at once
radio telescopes must be larger than optical telescopes because
A radio sources are much weaker
B radio waves are much longer
C the complicated equipment takes up a great deal of room
D radio astronomers are better fund raisers
radio astronomy is useful because
A it allows us to see objects we would not or could not see optically
B it helps satisfy scientists' passion for spending money
C it allows us to study normal stars in a new color
D no choice
which of the following suffers from curvature of field:
A refracting
B reflecting
C schmidt
D gregorian
the most important feature of an astronomical telescope is its ability to
A gather light
B produce a magnified image
C resolve close objects
D image large parts of the sky at once
which of the following devices receives and detects radio waves
A a refracting telescope
B the human eye
C a television set
D an audio microphone
the main drawback of a radio telescope to an optical telescope of the same size is that the radio telescope
A cannot operate at night.
B needs to have a radio receiver as a detector.
C has a lower resolving power.
D has a lower magnifying power.
E has a much larger weight.
which one of the following is a disadvantage of a refractor compared with a reflector of the same diameter?
A the refractor has a lower light gathering power
B the refractor will have a longer focal length
C the location of the refractor's focus depends on wavelength
D all the above are disadvantages of refractors
the most important power of a telescope for astronomy is
A light gathering power
B chromatic aberration
C electrical power
D computer power
to break white light into its colors, most spectroscopes use a
A slit
B collimator
C lens
D prism
which of the following telescopes has the worst chromatic aberration
A a prime focus reflector
B a cassegrain reflector
C a schmidt camera
D a refractor
a refracting telescope
A bends light as it passes through lenses
B reflects light from mirrors
C uses both lenses and mirrors
D no choice
in terms of the number of times light is lost from the beam, which of the following is the most efficient
A primary focus
B newtonian focus
C cassegrain focus
D coude focus
which of the following aberrations would most affect a reflecting telescope with a parabolic mirror?
A coma
B spherical aberration
C chromatic aberration
D none of the above
new telescopes currently being designed may use
A metal mirrors.
B computer controlled optics.
C lenses rather than mirrors.
D all of these.
the light-gathering power of a telescope is related directly to
A the image quality of its optics (resolution)
B the focal length of its primary mirror or lens
C the ratio of the focal lengths of its primary element (mirror or lens) and its eyepiece
D the area of its primary mirror or lens
bifurcating shutters
A are among the oldest types of shutters used on telescope domes
B present difficult engineering problems
C are used only with small telescopes
D no choice
which type telescope is, in general, the largest?
A infrared telescope.
B visible light telescope.
C ultraviolet telescope.
D radio telescope.
E no general statement can be made.
which of the following is not usually part of a prism spectroscope
A prism
B telescope
C collimator
D mirror?
the function of a telescope that is not directly dependent on the size of the objective is
A resolving power.
B magnification.
C light-gathering power.
D none of the above.
which of the following is not an advantage of radio telescopes over optical telescopes?
A can be used in cloudy weather.
B have greater resolution.
C allow invisible objects to be studied.
D easier to construct large radio telescopes.
which of the following telescopes would suffer most seriously from chromatic aberration
A a 10 inch schmidt
B a 40 inch refractor
C a 20 inch reflector
D a 40 inch reflector
large refracting telescopes cannot be built because
A glass is too expensive
B they are too long
C lenses can only be supported around the edges and glass sags
D large mirrors cannot be made smooth enough
astronomers are interested in magnifying an image
A almost always
B whenever they want to find more stars
C only when looking at objects which have some finite apparent area
D no choice
select the most appropriate phrase for an x-ray telescope
A only useable above the Earth's atmosphere
B is easily used during the day on Earth
C an objective lens collects light
D an astronomer standing next to an unshielded telescope would be a source o interference
which of the following telescopes in space was especially designed to observe x-rays?
A IUE
B IRAS
C Einstein
D space telescope
select the most appropriate phrase for a radio telescope
A an astronomer standing next to an unshielded telescope would be a source o interference
B is easily used during the day on Earth
C an objective lens collects light
D only useable above the Earth's atmosphere
which property of glass is used in the prism of a spectroscope
A ability to focus an image
B chromatic aberration
C ability to reflect some light while transmitting some
D transparency
the 48 inch schmidt telescope is superior to the 200 inch hale telescope in terms of its
A light gathering power
B field of view
C resolving power
D freedom from chromatic aberration
where would be the best place to locate a telescope for observing gamma rays from celestial objects?
A near the ocean
B in a desert far from cities
C on a mountain top
D on a space station
astronomers practice invisible astronomy because
A many astronomical objects emit outside of the visible.
B most electromagnetic radiation at the Earth is invisible.
C most of the electromagnetic spectrum is invisible.
D (a) and (b)
E (a) and (c)
select the most appropriate phrase for an infrared telescope
A is easily used during the day on Earth
B only useable above the Earth's atmosphere
C an astronomer standing next to an unshielded telescope would be a source o interference
D an objective lens collects light
to increase the light gathering power of a telescope, you must
A lengthen the telescope tube
B increase the accuracy of the optical surfaces
C attach a spectroscope to the telescope
D increase the diameter of the main lens or mirror of the telescope
the largest optical telescope in the world is a
A reflecting
B refracting
C schmidt
D satellite
the resolution of individual radio telescopes is worse than that of good optical telescopes because
A radio telescopes are smaller
B radio telescopes operate at much longer wavelengths
C radio telescopes have shorter focal lengths
D radio telescopes have considerably more astigmatism
why do we place telescopes on satellites in Earth orbit to measure celestial x-rays?
A to escape interference from artificial sources of x-rays
B because celestial x-rays cannot reach the ground
C celestial x-ray observation are too dangerous from the ground
D no one has observed x-rays from space
the Russian 236 inch telescope, now under construction, can use an altazimuth mount because
A where it will be used the north celestial pole is directly overhead
B where it will be used the north celestial pole is on the horizon
C a computer will be used to make the mount track like an equatorial mount
D that is the type of mount used by most astronomical telescopes
in a refracting telescope, the way in which the light rays are bent depends most critically upon
A the shape of the objective lens
B the relative size of the objective lens and the eyepiece lens
C the shape of the primary mirror
D no choice
the main reason that large visible-light telescopes are placed upon high mountains is
A to avoid the scattered light produced by human habitation
B to allow astronomers to observe stars for longer periods between star-rise and star-set
C to reduce the effect of atmospheric turbulence upon the sharpness of star image
D to move the telescope closer to the stars
which of the following telescopes must be above Earth's atmosphere?
A a radio telescope
B an infrared telescope
C a VLBI telescope
D an x-ray telescope
the resolving power of a telescope refers to
A its ability to separate two sources that are close together
B its ability to settle disputes
C the ratio of focal length to the diameter of the occular(in cm)
D its chromatic aberration
a telescope that suffers from chromatic aberration and low light-gathering power is probably
A a small-diameter reflector.
B a large-diameter reflector.
C a small-diameter refractor.
D a large-diameter refractor.
a telescope on the moon would have advantages over Earth-based telescopes because
A it would be closer to the stars
B it would be outside of the Earth's atmosphere
C an equatorial mount would not be necessary
D the zenith would be higher in the sky
balloons are sometimes used to carry aloft infrared telescopes
A to see objects beyond the horizon
B to get larger collecting areas
C to calibrate the telescope's readings
D to get above the atmosphere's murkiness in the infrared
the resolving power of a telescope is a measure of its
A magnification under good conditions.
B overall quality.
C ability to distinguish details in an object.
D all of the above.
the greater the _____ the greater the resolution of a telescope
A objective focal length
B eyepiece focal length
C objective diameter
D magnification
a high dispersion spectrograph is not always desirable because
A not enough detail is present
B not enough light is available
C they are not accurate
D no choice
which of the following causes there to be a limit to the useful magnification of a given telescope?
A diffraction of light.
B red shift of distant objects.
C there is a limit to how well lenses can be made.
D reflection of light from parts of the telescope.
the purpose of the eyepiece in a telescope is to
A disperse light
B cause chromatic aberration
C collect or gather light
D magnify the image
the main reason for building large optical telescopes on the Earth's surface is
A for national prestige, with no scientific reason
B to magnify images of objects and produce higher resolution photographs
C to bring astronomical objects closer for more detailed examination by scientists
D to collect more light from faint objects
what is "chromatic aberration"?
A the bending of light as it passes through a curved piece of glass
B the focusing of light of different colors to different points by a single lens
C the change in frequency, wavelength, and energy of the photons that pass through glass
D the deviation of light rays from straight trajectories caused by their passage through a
convex lens
a radio telescope can utilize metal mesh, with holes a few millimeters in diameter, rather than a solid surface to form its "dish" because
A the purpose of the dish is to detect, rather than to concentrate, the radio waves
B the holes allow the radio waves to go through to the detector array beneath the dish
C radio waves have a wavelength larger than the holes in the mesh
D none of the above
astronomy from space vehicles is particularly useful because
A the telescope is above the Earth's absorbing and distorting atmosphere and can measure radiation over a very wide wavelength range
B the telescope moves smoothly in a constant orbit, and can produce sharp photographs
C the telescope is in a gravity-free state, the mirror is not distorted by gravitational stress, and can produce sharper images
D the telescope is in a clean, dust-free environment and scattered light is much reduced
astronomers generally prefer to use reflecting telescopes rather than refracting telescopes because
A the two lenses in a reflecting telescope bring light of all colors to focus at more nearly the same place
B reflecting telescopes do not produce chromatic aberration
C reflecting telescopes are always smaller than refracting telescopes and the are more compact
D none of the above; refractors are superior to reflectors in all ways
in the largest telescope that is used to collect visible light, the device that collects the radiation is a
A lens
B fine wire mesh
C prism
D mirror
a recent, revolutionary advance in astronomy is the development of
A telescopes powerful enough to produce images of the surfaces of stars
B charge coupled devices (CCD)
C portable telescopes that can be moved from place to place on Earth
D visible light telescopes that can be used during the daytime from Earth
chromatic aberration is a failing of a telescope objective to bring all colors of light to the same focus, and appears
A in all telescopes, since it is a basic property of light
B only in a reflecting telescope
C in both reflecting and refracting telescopes
D only in a refracting telescope
the primary reason why astronomers generally prefer to use large telescope is because
A they magnify better than small ones
B they provide brighter images than do small ones
C they are always made using lenses instead of image-inverting mirrors
D they are impressive
a telescope that suffers from chromatic aberration and low light-gathering power is probably
A a small-diameter reflector
B a large-diameter reflector
C a small-diameter refractor
D a large-diameter refractor
a refracting telescope is the type which uses as its main optical element
A a lens
B a prism of glass
C a mirror
D a combination of many small plane mirrors
the main reason for building larger astronomical telescopes for visible light observations on the Earth's surface is to
A increase the sharpness of the images of distant objects
B filter out more of the scattered light from Earth
C collect more light from distant objects
D magnify the images of distant objects
chromatic aberration occurs in a refracting telescope when
A the lenses bend under their own weight and thereby distort the final image
B light from some wavelengths is absorbed by the lenses, thereby creating false colors of objects
C some wavelengths are scattered out of the telescope by imperfections in the glass in the lenses
D all colors of light are not focused at the same position
the most important power of an astronomical telescope is its ability to
A make things look upside down
B collect light
C make things look bigger
D none of these
major observatories are usually located at high altitude because
A this gets the telescopes above some of the atmosphere's obscuring effects
B it reduces gravitational distortions in the mirror shapes
C it gets the telescopes closer to the target objects
D it allows x-rays to be observed from the ground
the reason that the mirror of a reflecting telescope can be made larger than the lens of a refracting telescope is that
A the mirror is made of stronger material than the lens
B the mirror can be supported from behind, while the lens cannot
C the mirror has a greater light-gathering power than the lens
D the lens must be made of several parts to overcome the effects of chromatic aberration
a telescope which uses lenses to concentrate light is
A a refracting telescope
B a reflecting telescope
C a newtonian telescope
D a cassegrain telescope
what is the main reason that astronomers want to build larger telescopes?
A greater magnifying power.
B greater resolving power.
C greater light-gathering ability.
D bigger telescopes can detect more of the spectrum.
E bigger appropriations from the federal government.
what is the main reason that radio interferometers, such as the very large array, use several radio antennas spread over a large area?
A to increase magnifying power.
B to increase resolving power.
C to increase light-gathering power.
D to increase the amount of land needed for the telescope.
suppose that you own a reflecting telescope. which of the following characteristics of the telescope could you most easily change?
A magnifying power.
B light-gathering power.
C resolving power.
D use of a mirror as an objective.
the major cause of blurring and unsharp images of objects observed through very large telescopes, at the extreme limit of magnification, is
A air turbulence in the Earth's atmosphere
B the poor optical polish achievable on large mirrors
C the clumsiness of the telescope operator
D the poor tracking capabilities of modern telescopes
in general, radio telescopes are much larger than optical telescopes. one basic reason for this difference is that
A radio waves are much less energetic than light.
B radio waves are much longer in wavelength than light.
C radio receivers do not detect radio waves very well.
D radio antennas do not reflect very well.
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