1. Practice Questions Electromagnetic Spectrum

2. The electromagnetic spectrum Figure 3.5 Identify the following portions of the Electromagnetic spectrum: A B D E C

3. The electromagnetic spectrum Figure 3.5 Which end of the spectrum is more energetic, A or B? Why? A B

4. Light has a DUAL NATURE! “photon” wave &

5. If the Hydrogen gas cloud is moving towards Earth, the absorption line marked will shift in which direction? BA An absorption line of Hydrogen measured at rest

6. How do light and matter interact? KNOW THESE DEFINITIONS! Emission Absorption Transmission Reflection or Scattering

7. What types of light spectra can we observe? 1. Continuous spectra 2. Absorption spectra 3. Emission spectra

8. Which is the absorption spectrum?

9. Which is the continuous spectrum?

10. Which is the emission spectrum?

11. BLUE Yellow RED BLACK Which spectrum is coming from the coolest object?

12. BLUE Yellow RED BLACK The object producing the yellow spectrum might be what type of star?

13. BLUE Yellow RED BLACK Is the star producing the yellow or red spectrum hotter? Why?

14. BLUE Yellow RED BLACK Which spectrum is coming from the hottest object?

15. Which star is more luminous? T = 15,000 K Radius = 1 unit T = 15,000 K Radius = 2 units

16. Which star is more luminous? T = 3,000 K Radius = 1 unit T = 15,000 K Radius = 1 unit

17. REMEMBER! Luminosity of a star is intrinsic. Depends on Temperature & Radius.

18. For which stars would we observe a Doppler Shift? A B C

19. Doppler shift Figure 3.18

20. Doppler Effect Summary Motion toward or away from an observer causes a shift in the observed wavelength of light: blueshift (shorter wavelength)  motion _______ you redshift (longer wavelength)  motion AWAY from you greater shift  greater speed

21. Doppler Effect Summary Motion toward or away from an observer causes a shift in the observed wavelength of light: blueshift (shorter wavelength)  motion toward you redshift (longer wavelength)  motion ______ from you greater shift  greater speed

22. How do telescopes help us learn about the universe? Telescopes collect more light than our eyes  light-collecting area Telescopes can see more detail than our eyes  angular resolution Telescopes/instruments can detect light that is invisible to our eyes (e.g., infrared, ultraviolet)

23. The energy source for the sun is A. combustion of hydrocarbons B. solar flares C. nuclear fission, the splitting of two hydrogen atoms D. nuclear fusion, the joining of two hydrogen atoms E. combustion of hydrogen

24. The energy source for the sun is A. combustion of hydrocarbons B. solar flares C. nuclear fission, the splitting of two hydrogen atoms D. nuclear fusion, the joining of two hydrogen atoms E. combustion of hydrogen

25. The hotter an object A. the brighter it appears at all wavelengths, and the longer the wavelength at which it appears brightest B. the shorter the wavelength at which it appears brightest C. The brighter it appears at all wavelengths, and the shorter the wavelength at which it appears brightest D. the longer the wavelength at which it appears brightest E. the brighter it appears at all wavelengths

26. The hotter an object A. the brighter it appears at all wavelengths, and the longer the wavelength at which it appears brightest B. the shorter the wavelength at which it appears brightest C. The brighter it appears at all wavelengths, and the shorter the wavelength at which it appears brightest D. the longer the wavelength at which it appears brightest E. the brighter it appears at all wavelengths

27. An object emits an emission line spectrum. If the object moves towards an observer, A. the observed emission lines shift to shorter wavelengths B. the observed emission lines shift to longer wavelengths C. the emission line spectrum shifts to a continuous spectrum D. the emission line spectrum shifts to an absorption line spectrum

28. An object emits an emission line spectrum. If the object moves towards an observer, A. the observed emission lines shift to shorter wavelengths B. the observed emission lines shift to longer wavelengths C. the emission line spectrum shifts to a continuous spectrum D. the emission line spectrum shifts to an absorption line spectrum

29. Which of the following is ordered by increasing wavelength? A. infrared, visible, radio, gamma-ray B. visible, infrared, radio, gamma-ray C. gamma-ray, visible, infrared, radio D. radio, visible, infrared, gamma-ray

30. Which of the following is ordered by increasing wavelength? A. infrared, visible, radio, gamma-ray B. visible, infrared, radio, gamma-ray C. gamma-ray, visible, infrared, radio D. radio, visible, infrared, gamma-ray

31. An atom is ionized if A. it has lost a proton B. it has lost an electron C. it has lost a neutron D. it has absorbed a photon

32. An atom is ionized if A. it has lost a proton B. it has lost an electron C. it has lost a neutron D. it has absorbed a photon