Astronomy Chapter 5 Test Questions – Flashcards
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What is the primary purpose of an astronomical telescope? Select one: A. to magnify and make distant objects appear closer Incorrect B. to measure the intensity of light very accurately C. to separate light into its component colors D. to collect a lot of light and bring it to a focus E. to access wavelengths that we cannot see visually
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D. to collect a lot of light and bring it to a focus
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Why are most large telescopes reflectors, not refractors? Select one: A. Reflectors do not suffer from chromatic aberration like refractors do. B. Large mirrors need only one optical surface, achromats four surfaces to grind. C. Large lenses deform under their own weight, but mirrors can be supported. D. Large, very clear lenses are harder to cast than more tolerant mirror blanks. E. All of the above are correct.
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E. All of the above are correct.
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Which design has a convex primary mirror and flat secondary mirror, with the eyepiece located on the top side of the telescope tube? Select one: A. refractor B. interferometer C. Newtonian reflector D. prime focus reflector E. Cassegrain reflector
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C. Newtonian reflector
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The amount of diffraction, and thus the resolution of the scope, depends upon: Select one: A. the brightness of the object. B. the size and sensitivity of the CCD chip used for imaging. C. the design of the telescope. D. the wavelength used and the size of the main telescope objective lens or mirror. E. whether the telescope is a reflector or refractor.
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D. the wavelength used and the size of the main telescope objective lens or mirror.
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The angular resolution of an 8-inch diameter telescope is ________ greater than that of a 2-inch diameter telescope. Select one: A. 9 times B. 16 times C. 8 times D. 2 times E. 4 times
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E. 4 times
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It is diffraction that limits the ________ of a telescope's objective. Select one: A. frequencies B. resolution C. wavelengths D. light grasp E. magnification
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B. resolution
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What is the resolution of a telescope? Select one: A. its ability to separate light into its component colors for analysis B. its ability to make distant objects appear much closer to us C. its ability to distinguish two adjacent objects close together in the sky D. its ability to see very faint objects E. its ability to focus more than just visible light for imaging
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C. its able to distinguish two adjacent objects close together in the sky
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What is the resolving power of the telescope? Select one: A. the ability to collect a lot of light B. the ability to separate light into its component colors C. the ability to make distant objects appear closer D. the ability to distinguish adjacent objects in the sky E. the ability to detect very faint objects
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E. the ability to detect very faint objects
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What is the light-gathering power of an 8-inch telescope compared to a 4-inch telescope? Select one: A. 4× better B. 16× better C. 2× better D. 32× better E. 8× better
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A. 4x better
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The process occurring when photons bounce off a polished surface is called: Select one: A. interference. B. dispersion. C. refraction. D. reflection. E. diffraction.
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D. reflection
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A telescope with a 60 mm objective lens collects how many times as much light as does your eye's 6 mm exit pupil? Select one: A. 100 times B. 25 times C. 10 times D. 5 times E. 250 times
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A. 100 times
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How much better resolution would a 60 mm objective lens have than your eye's 6 mm exit pupil? Select one: A. 6 times B. 100 times C. 10 times D. 60 times E. 16 times
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C. 10 times
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Diffraction is the tendency of light to: Select one: A. separate into its component colors. B. spread around corners. C. reflect off a mirror. D. bend through a lens. E. disperse within a prism.
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B. spread around corners.
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It is diffraction that limits the ________ of a telescope of a given objective diameter. Select one: A. magnification B. interference C. resolution D. aperture E. light grasp
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C. resolution
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What are two advantages of large scopes over smaller ones? Select one: A. Large telescope have more light grasp and better resolution. B. Large scopes have a larger field of view and sharper focus. C. Large scopes are not subject to atmospheric turbulence and opacity like smaller ones. D. Large telescopes give higher magnification and are easier to build. E. Large scopes are easier to mount and control than small ones.
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A. Large telescope have most light grasp and better resolution.
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The amount of diffraction a telescope creates depends upon: Select one: A. the transparency of the atmosphere. B. the magnification of the eyepiece. C. the wavelength and the diameter of the telescope objective. D. the types of glass used in the achromat. E. whether the telescope is a refractor or a reflector.
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C. the wavelength and the diameter of the telescope objective.
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Refractor telescopes suffer from this separation of light into its component colors. Select one: A. spherical aberration B. bad seeing C. limited diffraction D. refraction E. chromatic aberration
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E. chromatic aberration
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One advantage of the Hubble Space telescope over ground based ones is that: Select one: A. it can make better observations of the ozone layer. B. it can better focus X-ray images. C. its adaptive optics controls atmospheric blurring better. D. in orbit, it can operate close to its diffraction limit at visible wavelengths. E. it is larger than any Earth-based scopes.
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D. in orbit, it can operate close to its diffraction limit at visible wavelengths.
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A mountain top is an especially good site for infrared telescopes since: Select one: A. there you are closer to celestial objects. B. you are above most of the carbon dioxide and water vapor in the atmosphere. C. less air above means better seeing in many cases. D. the cold weather helps the sensitivity of infrared detectors. E. All of the above are factors.
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E. All of the above are factors.
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What is true of radio telescopes? Select one: A. They have better angular resolution than a reflector. B. They can only be used above the atmosphere. C. They are the smallest, most compact telescopes. D. They are most sensitive to the opacity of the ozone layer. E. They have poorer angular resolution than a refractor.
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E. They have poorer angular resolution than a refractor.
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Which design is subject to chromatic aberration? Select one: A. Cassegrain reflector B. prime focus reflector C. Gregorian reflector D. Newtonian reflector E. refractor
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E. refractor
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Which of the following is a problem inherent in all large radio telescopes? Select one: A. The lightest breeze shakes them, making the observations blurry. B. Radio waves have long wavelengths, so radio telescopes have poor resolution. C. The dust clouds in the Milky Way block almost all wavelengths except light. D. Their waves are blocked by water vapor, so they must be located in deserts. E. They are badly affected by poor seeing and atmospheric turbulence.
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B. Radio waves have long wavelengths, so radio telescopes have poor resolution.
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Radio dishes are large in order to: Select one: A. detect shorter waves than optical telescopes for superior resolution. B. increase their angular resolution and collect the very weak radio photons. C. increase the range of waves they can collect. D. attract funding from NASA and the NSF. E. give greater magnification.
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B. increase their angular resolution and collect the very weak radio photons. (probably on test)
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Compared to optical telescopes, radio telescopes are built large because: Select one: A. radio photons don't carry much energy. B. atmospheric turbulence is more of a problem. C. radio sources are harder to find. D. they're less expensive to make than optical telescopes. E. radio waves are absorbed by the atmosphere.
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A. radio photons don't carry much energy.
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In astronomy, an interferometer can be used to: Select one: A. increase the sensitivity of infrared telescopes to longer wavelengths. B. improve the angular resolution of radio telescopes. C. yield better seeing conditions with optical telescopes. D. speed up the processing of CCD images. E. decrease the effects of light pollution in getting darker sky backgrounds.
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B. improve the angular resolution of radio telescopes.
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In which part of the electromagnetic spectrum have astronomers been unable to get any information? Select one: A. X-rays B. ultraviolet C. microwaves D. gamma rays E. We now can access information in all spectral lengths.
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E. We now can access information in all spectral lengths.
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The design of modern X-ray telescopes depends on: Select one: A. the Cassegrain design, with mirrors made of lead. B. achromatic lenses to keep the X-rays in focus. C. the prime focus design, with mirrors made of iron. D. lenses made of germanium. E. grazing incidence optics.
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E. grazing incidence optics.
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The tendency of a wave to bend as it passes from one transparent medium to another is called: Select one: A. refraction. B. reflection. C. diffraction. D. interference. E. dispersion.
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A. refraction.
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The primary purpose of a telescope is to: Select one: A. make distant objects appear nearby. B. measure the brightness of stars very accurately. C. collect a large amount of light and bring it into focus. D. separate light into its component wavelengths. E. magnify distant objects.
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C. collect a large amount of light and bring it into focus.
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What problem do refractor telescopes have that reflectors don't? Select one: A. chromatic aberration B. spherical aberration C. diffraction limited resolution D. light loss from secondary elements E. bad seeing
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A. chromatic aberration (probably on test)
