Chapter 4: Light

Study Plan

Unlike the physicist or the chemist, who has control over the conditions in a laboratory, the astronomer must try to glean the secrets of the universe from the light and other particles such as neutrinos that reach us from distant objects. On this leg of our journey we turn our attention to light, a most informative messenger, and find that

  • Light is an electromagnetic wave with a spectrum extending far beyond the colors of the rainbow.
  • Light is also a stream of particles called photons.
  • Reconciling the wave and particle nature of light and matter points beyond Newton's physics and challenges our everyday ideas about what is "real." Measurements of the speed of light also require that we think beyond classical physics and reassess our understanding of time and space.
  • The wave/particle nature of light and matter gives different types of atoms unique spectral "fingerprints" that we can use to measure the composition and properties of distant objects.
  • Temperature measures the thermal energy of an object and determines the amount and spectrum of light that a dense object emits.
  • Light is not only a messenger but is also a way in which energy is carried throughout the universe.

Organize

  1. Read Chapter 4 in your textbook or ebook.
  2. Take the Diagnostic Quiz to assess your understanding of the basic concepts and identify gaps in your understanding of the assigned reading.

Learn

  1. Access the Animations given for this chapter. These brief lessons enhance your understanding of core concepts.
    AnimationDoppler Effect
    Section: 4.4
  2. Use the FlashCards to test your memory for new terms.
  3. Review Foundations Box 4.1: Uncertainty Is Ordinary in the Quantum World, and Box 4.2: Equilibrium Means Balance.
  4. Work the "Thinking about the Concepts" and "Applying the Concepts" questions in the end of chapter review materials.
  5. If your instructor has assigned SmartWork online homework, login from the right navigation pane for additional practice and review.

Connect

  1. Periodic Connections boxes and the Seeing the Forest through the Trees section at the chapter's end draw your attention to recurring themes and help prepare you for concepts explored more fully in subsequent chapters.
  2. Visit Astronomy in the News for breaking news of new discoveries and the opportunity to apply what you've learned in this chapter to real-world (and real Universe) events.


Section Menu

Organize

Learn

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