Flashcards
Physics 5 - diffraction
Flashcards do conjunto (20)
- 1Why do telescopes need to be large? What is this because of?-In order to pick up faint objects, as well as to create detailed images
-Diffraction - 2What is diffraction?-The effect of waves spreading out as they pass through a small gap or go round an object
- 3When do we notice diffraction most?-When the gap is about the same size as the wavelength of the wave
- 4Bigger or smaller gap = more diffraction?-Smaller
- 5How does wavelength affect diffraction?-The larger the wavelength the more it diffracts
- 6what does a radio telescope detect? What does an X-ray telescope detect?-Large wavelengths
-Wavelengths much smaller than light - 7What is the aperture of a telescope?-The size of the objective lens/mirror
- 8How does a diffracted image of a star appear? Why?-A central image surrounded by blurry rings
-Because the aperture of a telescope is round - 9Why does the aperture need to be large?-In order to create sharp images
-To do this, the aperture must be much larger than the wavelength of the waves - 10Diffraction affect on radio telescopes? Why? solution?-Means they have to be reaaaalllly big
-Because radio waves have very large wavelengths
-Conjoining multiple telescopes to create a large aperture - 11What does a stars spectrum show?-How much energy of each wavelength it emits
- 12What can studying the spectrum of radiation of a star tell us about?-Its composition and temperature
- 13How can separate light into a spectrum of colours? Why does this work?-Prism
-Because different wavelengths of light are refracted by different amounts - 14Effect of wavelength on refraction?-The smaller, the more refracted
- 15How else can a spectrum be produced?-Via a diffraction grating
- 16What is a diffraction grating?-A series of very small gaps that light can shine through
OR
-A series of finely spaced lines on a reflective surface - 17How does a diffraction grating work?-Different wavelengths of light are diffracted by different amounts as they shine through it
- 18What did astronomers notice when they discovered quasars? What did this mean?-Their line spectrum was shifted to the red end
-They were travelling at high speeds away from us, and must have been very far away - 19Why did some astronomers not agree with this theory of redshift?-They thought it was not possible to see objects so distant, and therefore that something else must be causing the effect
- 20What are quasars? How long did it take for this idea to become accepted?-The brightest and most distant objects in our universe
-20 years
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- Physics FlashCards sobre Physics 5 - diffraction, criado por Harry Mercer em 22-06-2017.
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- Harry Mercer
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