1. Using, scientists can use a few smaller telescopes to take images with the. 2. To double the resolving power of a telescope, you must.

Transcription

1 Chapter 5 Telescopes Multiple Choice Questions 1. Using, scientists can use a few smaller telescopes to take images with the same resolution as a much larger telescope. A. Satellite telescopes B. Charge-coupled devices (CCDs) C. Interferometry D. Adaptive optics 2. To double the resolving power of a telescope, you must. A. Increase the diameter by a factor of two B. Increase the collecting area by a factor of two C. Decrease the diameter by half D. Decrease the collecting area by half 3. A warm dust cloud in which stars are forming would be best observed with a(n) telescope. A. Radio B. Gamma-Ray C. Infrared D. Optical (visible light) 4. A galaxy with almost no starlight but plenty of cool clouds of hydrogen gas would be best observed with a(n) telescope. A. X-ray B. Radio C. Infrared D. Optical (visible light)

2 Chapter 5 Telescopes Study Guide 5. In a false color image, A. Only one color is used. B. Color information from optical telescopes is combined with information from a non-visible wavelength telescope to make the image. C. Stars appear black and the background appears white. D. Colors can represent photon energies or the intensity of electromagnetic radiation. 6. Ignoring the effects of the atmosphere, what is the theoretical resolution of an 8 inch telescope (about 20 cm) if you are looking at visible light with a wavelength of about 500 nm? A. About half an arcsecond. B. About half a degree. C. About 1/100 of an arcsecond. D. About 25 arcseconds. 7. If your pupils have a diameter of about 5mm, about how many times more light gathering power does a telescope with a diameter of about 20 cm (8 inches) have than your pupils? A. 4 times B. 16 times C. 40 times D. 160 times E times 8. The resolving power of a telescope is affected by the property of light called A. Refraction. B. Diffraction. C. Reflection. D. Seeing. E. Attenuation. 9. One of the biggest problems for ground based astronomy today is A. All the best mountains already have telescopes on them. B. Atmospheric pollution has significantly worsened the seeing. C. Space-based observatories are making most of the observations. D. Light pollution makes it difficult to observe faint objects.

3 10. The two most important properties of any telescope are A. The light gathering power and the length of the tube. B. The length of the tube and the magnification. C. The magnification and the light gathering power. D. The resolving power and the magnification. E. The light gathering power and the resolving power. 11. A pencil inside a water glass appears to be bent because of A. Reflection of light. B. Refraction of light. C. Diffraction of light. D. None of the above. 12. Why does the Sun look flattened near the horizon? A. The Sun's light is reflected off the horizon, making the Sun appear compressed. B. The Earth's dense atmosphere compresses the gaseous Sun. C. The larger refraction near the horizon lifts the lower edge of the Sun more than the upper edge and makes the Sun look flattened. D. The Sun is cooler on the horizon, so it looks flattened. 13. Why does the Moon appear bigger near the horizon? A. Due to an optical illusion. B. Due to refraction. C. Due to reflection. D. Due to the compression produced by the Earth's atmosphere.

4 14. What is a disadvantage of using a single, large lens in a telescope? A. Large lenses are expensive to fabricate. B. A lens has to be supported only at its edges, so the lens can sag in the middle. C. Different colors of white light on passing through a lens focus at different points and result in a blurred image. D. Some lens materials completely absorb short wavelengths. E. All of the above. 15. The ability of a telescope to show two very close objects separately is called its. A. Light gathering power B. Resolving power C. Magnification D. None of the above 16. Carl has a 5-inch refracting telescope and Jim has a 3-inch reflecting telescope. Whose telescope has a higher light-gathering power? A. Carl's, because lenses gather more light. B. Jim's, because mirrors gather more light. C. Carl's, because the larger the diameter, the more light to be collected. D. Jim's, because the smaller the diameter, the more light to be collected. 17. Tom has a 4-inch refracting telescope and Steve has a 3-inch reflecting telescope. Whose telescope has a higher resolving power? A. Tom's, because lenses are more efficient in showing the objects separately. B. Steve's, because mirrors are more efficient in showing the objects separately. C. Tom's, because the larger the diameter, the better the resolution. D. Steve's, because the smaller the diameter, the better the resolution.

5 18. What is "seeing"? A. The ability of a telescope to show two very close objects separately. B. The capacity of a telescope to gather more light. C. The ability of a telescope to see in the night. D. The distortion of an image due to an atmospheric turbulence. 19. The best site for placing an X-ray telescope is. A. A mountain top B. A valley C. Near an ocean D. A desert E. Above the Earth's atmosphere 20. The best site for placing a ground-based optical telescope is. A. A mountain top B. A valley C. In an urban setting D. in a location that has few sunny days throughout the year. 21. An interstellar gas is emitting 10-centimeter wavelength radiation and a nearby star is emitting 10-micrometer wavelength radiation. Which of these can you observe through an Earth-based telescope? A. The interstellar gas B. The star C. Both of them D. Neither of them 22. X-rays are blocked by and present in the Earth's atmosphere. A. Water molecules; carbon dioxide B. Ozone; oxygen C. Nitrogen; helium D. Electric charges; clouds

6 23. Why do stars twinkle? A. Due to rapid changes occurring on their surfaces. B. Due to their movement across the sky. C. Due to the refraction caused by atmospheric irregularities. D. Due to imperfections in the human eye. 24. Which is the most efficient means of recording light? A. Photographic films B. Photomultiplier tubes C. Charge-coupled device (CCD) D. The human eye 25. Which space telescope is observing X-rays? A. The Hubble Space Telescope (HST) B. The Chandra Observatory C. The Spitzer Space Telescope D. The Extreme Ultraviolet Explorer (EUVE) 26. Which of the following is an inherent disadvantage of radio telescopes? A. Radio telescopes cannot detect visible light. B. Radio telescopes have low magnification. C. Radio signals are very weak, and their photons do not penetrate the atmosphere easily. D. The long wavelength of radio waves results in lower resolving power, compared to other telescopes of the same size. E. They only work at night. 27. Which of the following telescopes is most suitable for observing cool gas clouds? A. X-ray telescope. B. Radio telescope. C. Visible light telescope. D. All of the above. E. Cool gas clouds cannot be observed by telescopes.

7 28. is the most important quality of an astronomical telescope. A. Magnification B. Resolving power C. Ability to see at night D. Rigidity 29. If a 3 meter diameter telescope is doubled in size, then its new light collecting power would A. Not change. B. Double. C. Increase by a factor of four. D. Reduce by half.