رد: رح ــلة من التكميلي إلى التخرج..},تجمع طلبة وطالبات ماستر علوم فلكية
السلام عليكم ورحمة الله وبركاته
منورنا استاذنا وشرفتنا بمداخلتك الجميله ق1
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علياء الله يخليكي المحاولات حق البروف حطيها هنا ابغى اشوف انتي كيف حليتي لاني موعارف كيف ابدا فيه اصلا
وهذا حل شابتر 4
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Ch4
1. How does a spectrograph work?
light passes through the slit , Then up to prism Which by breaking light into spectra that make it up. .
2. Why is the diffraction grating more efficient than prism?
1- refracts light so no photons are "lost".
2- linear a prism disperses blue light much more than in the red .
3- Gratings can also reflect light in the UV wavebands unlike a glass prism which is opaque to UV
3. What are the tools of recording the celestial object spectrum?
charged-couple device (CCD)
Photographic spectra
4. What are the advantages of using the modern astronomical charged-couple devices?
1- can reach a quantum efficiency of about 90% compared with about 1% for photographic emulsions.
2- can convert almost 9 out of 10 incident photons into useful information compared with about 1 in 100 for film
3- can therefore obtain a useful spectrum much quicker than using a photographic plate
4- can obtain spectra from much fainter sources
5. What are the information of radio spectra and not available in visible spectra?
1-Radio spectral data can give details about frequency and velocity.
2-It can also provide information about the polarization of the signal,
6. What is the key advantage of multifibre technique?
A key advantage of this technique is that more than one spectrum can be obtained simultaneously
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