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26 Cards in this Set
- Front
- Back
What is the light gathering power of an 8 inch telescope compared to a 4 inch telescope? |
4 time better |
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If the rest wavelength of a certain line is 600 nm, but we observe it at 588 nm, then: |
The object is approaching you at 2% the speed of light |
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Which type of telescope has the simplest light path? |
Prime focus reflector |
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all modern large optical telescopes are refractors |
False (they are reflectors) |
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Green light has a shorter wavelength than orange light. In a 5 inch telescope, green light will: |
provide better angular resolution than orange light |
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One advantage of the Hubble Space telescope over ground based ones is that: |
In orbit, it can operate close to its diffraction limit at visible wavelengths |
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Optical telescopes are usually used only at night, but radio telescope can be used day or night. |
True |
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Which of the following is a reason to use a reflecting telescopee rather than a refractor? |
Lenses absorb light, while mirrors do not. A lens must have two precision surfaces, a mirror only needs one. Keavy lenses, which can only be supported at their edges, tend to deform under their own weight. Lenses are subject to chromatic aberration. |
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The amount of diffraction and thus the resolution of the telescope depends upon: |
the wavelength used and the size of the main telescope objective lens or mirror. |
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In the Doppler effect, a red shift of spectral lines shows us the soruce is receding from us: |
True |
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What is true of radio telescopes? |
They have poorer angular resolution than a refractor of the same size |
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Galaxies look the same whether viewed in visible or X-ray wavelengths
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False |
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A telescope design that uses a lens and no mirrors is a refractor |
True |
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_________ optics greatly reduce the effect of atmospheric turbulence by deforming the shape of the mirror by computer control: |
Adaptive |
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In the future, adaptive optics will greatly enhance the resolution of the hubble space telescope. |
False |
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If a source of light is approaching us at 30,000 km/sec, then all of its waves are: |
Blue shifted by 10% |
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Compared to a 5 inch prime focus reflector, a 5 inch Newtonian reflector will: |
Have the same light gathering power |
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Stars do not twinkly, the instability of the atmosphere causes this: |
True |
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The ability of a telescope to seperate two closely spaced stars is called: |
Resolution |
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The primary purpose of a telescope is to |
Collect a large amount of light and bring it into focus |
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In astronomy, an interferometer can be used to: |
improve the angular resolution of radio telescopes |
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All optical telescopes will bring the light from a star to a focus: |
True |
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The observed spectral lines of a star are all shifted towards teh red end of the spectrum. |
This is an example of the Doppler Effect
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Grazing incidence optics are critical to focusing |
X-ray radiation |
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The angular resolution of an 8 inch telescope is _________ greater than that of a 2 inch diameter telescope:
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4 times more
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The light gathering ability of a telescope is most dependent on the diameter of its primary mirror/lens |
True |