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Chapter 4 Homework
1. What do materials like glass or water do to the speed of light
2. What is the wavelength range for Radio?
3. Which has a higher velocity – visible light or X-rays?
4. Which kinds of electromagnetic radiation have more energy?
5. Star A is blue, Star B is yellow, and Star C is red. Which one of these is the hottest star?
6. Hill's toy gun emits blue light, Johnson's emits red light, Rosenfeld's emits infrared light, and Vining'
emits ultraviolet light. Who has the most energetic toy gun? Defend your answer.
7. Give examples of objects that emit a spectrum very close to a blackbody spectrum?
8. What does it mean to say that the electrons are quantized in an atom?
9. What is the basic structure of an atom?
10. How can electrons in an atom jump from a lower energy orbital to a higher energy orbital?
11. You are heating a jar full of hydrogen and observing its spectrum. When you add more hydrogen to it,
what happens to the spectral lines in the spectrum?
12. What is a absorption spectrum and how does it differ from an emission spectrum?
13. If an object is moving very fast perpendicularly to your line of sight. What shift will you observe in its
spectrum?
14. Which electromagnetic waves are completely blocked by the Earth's atmosphere?
15. A star's emission line of 400 nm appears shifted to 404 nm in the spectrum. What can you conclude
from this shift?
16. What is an atmospheric window?
17. What is Wien's law and what does it apply to?
18. What determines the identity of a chemical element?
19. What happens when an electron in an atom absorbs a photon?
20. The Alpha star in the constellation of Orion shifts its position on the celestial sphere by 0.03 arc seconds
per year and the Beta star shifts by 0.001 arc seconds per year. Based on this observation, what conclusions
can be made?
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21. A gas emits a spectral line at 100 nm and another spectral line at 1000 nm. How do their energies
compare?
22. What does it mean to say something is blue-shifted?
23. What is a photon?
24. What force holds the electron in orbit around the nucleus of the hydrogen atom?
25. What makes up a hydrogen atom? A helium atom?
26. How does the energy of a photon of blue light compare to a photon of red light?
27. The wavelength of the red-pink line emitted by a laboratory sample of excited hydrogen is 656 nm.
Taking a spectrum of a glowing nebula, you find that the same red-pink line of hydrogen appears at 662
nm. What can you conclude about the nebula?
28. What happens when an oxygen atom loses 1 electron?
29. What type of light do night vision cameras utilize?
30. How does the conservation of energy apply to an atom that absorbs a photon?
31. Given that the Sun is 150 million kilometers from the Earth, how long does it take light to travel from
the Earth to the Sun?
32. Suppose you are operating a remote-controlled spacecraft on Mars from a station here on Earth. How
long will it take the craft to respond to your command if Mars is at its nearest point to Earth? Assume that
Mars is 0.52 AU’s away from the Earth (which is it’s closest approach).
33. A light bulb radiates most strongly at a wavelength of about 3000 nano-meters. How hot is its filament?
34. An electric stove burner on "high" radiates most strongly at about 2000 nanometers. What is its
temperature?
35. The Earth's temperature averaged over the year is about 300 Kelvin. At what wavelength does it radiate
most strongly? What part of the electromagnetic spectrum does this wavelength lie in? Can you see it?
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