SMT 314 - Introduction to Cosmology » Fall 2020 » HW3

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Question #1
A ground-based telescope to observe x-rays with x-ray detectors would:
A.   be worthless because no astronomical objects emit x-rays.
B.   be useful only to Superman, who has x-ray vision.
C.   be worthless because astronomers have not yet devised detectors sensitive to x-rays.
D.   give astronomers a chance to study the hot interiors of stars and planets.
E.   be worthless because x-rays cannot get through the Earth's atmosphere.
Question #2
All other things being equal, and ignoring atmospheric effects, a reflecting telescope with a large primary mirror will have, compared with a telescope with a smaller primary mirror:
A.   better light-gathering power but poorer angular resolution.
B.   better light-gathering power only.
C.   better light-gathering power and better angular resolution.
D.   no clear advantage unless the secondary mirror is also larger.
E.   better angular resolution only.
Question #3
Chromatic aberration is a problem in ________________ telescopes and refers to __________________.
A.   reflecting; the smearing of light due to atmospheric turbulence.
B.   reflecting; differing focal points from different parts of the mirror.
C.   refracting; different focal lengths for different wavelengths of light.
D.   space; the deformation of the glass due to the absence of gravity.
E.   refracting; the smearing of light due to atmospheric turbulence.
Question #4
Electronic gadgets called __________________, rather than photographic film, are now used almost exclusively to record optical images and spectra of astronomical objects.
A.   charge-coupled device
B.   semiconductor
C.   ROM
D.   RAM
Question #5
Substantial improvements have recently been made to narrow-field images made with ground-based telescopes by using the technique of _____________ ___________ (two words), which corrects for distortions in the waves of incoming light. (If you Google the answer, you will get it wrong.)
A.   fiber optics
B.   micro lens
C.   adaptive optics
Question #6
The ability to distinguish between details or to distinguish two adjacent objects as separate is known as ___________ ___________ (two words). (If it wasn't in the lecture, you will not receive any points, even if the answer is not incorrect.)
A.   radio waves
B.   gamma rays
C.   angular resolution
Question #7
Adaptive optics reduce the blurring of images by using smoother (better polished) mirrors.
A.   TRUE
B.   FALSE
Question #8
In some cases, radio telescopes at many different locations have been used together, combining the light, to produce images with much higher resolution than that of the individual telescopes
A.   FALSE
B.   TRUE
Question #9
The first optical telescopes ever made were refractors, but for most of all the past century the world's largest optical telescopes have been reflectors.
A.   FALSE
B.   TRUE
Question #10
The primary purpose of an astronomical telescope is to magnify images of stars and other objects.
A.   FALSE
B.   TRUE

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