By the conclusion of this chapter, you should be able to:
- Explain how light acts sometimes like a wave and sometimes like a particle.
- List the particles that compose atoms and summarize how the energy levels of an atom determine the wavelength of the light that the atom emits and absorbs.
- Describe how to measure the composition, properties, and motion of distant objects using the unique spectral lines of different types of atoms.
- Analyze how temperature measures the thermal energy of an object and determines the amount and spectrum of light that an object emits.
- Differentiate luminosity from brightness, and illustrate how distance affects each.
- Recognize how astronomical observations of different kinds of light provide different kinds of information about the universe.
Prepare and Assess
- Light as a Wave, Light as a Photon
- Atomic Energy Levels and the Bohr Model
- Atomic Energy Levels and Light Emission and Absorption
- The Doppler Effect
- EM Spectrum Module
Surveys the electromagnetic spectrum, showing a typical astronomical image for different wavelengths of light and the kind of instrument that would take such an image.
- Hydrogen Atom Simulator
Models a hydrogen atom and its interactions with light, demonstrating the quantum nature of absorption and emission.
- Three Views Spectrum Demonstrator
Demonstrates how different spectra can arise from a lightbulb (a thermal source) and a cold, thin gas cloud. The spectrometer shows emission, absorption, or continuous spectra based on where the movable telescope is pointed.
- Doppler Shift Demonstrator
Shows circular waves expanding from a source; movement of the source or observer affects the frequency of the waves seen by the observer, demonstrating Doppler shift.
- Blackbody Curves
Demonstrates how the blackbody spectrum varies with temperature. This explorer also shows how the relative intensities observed through different filters (a “color index”) can give an estimate of temperature.
- Blackbody Curves of Melting
This is a movie showing the heating and eventual melting of a nail, and the theoretical blackbody curve produced in the process.
- Flux Simulator
Demonstrates the inverse square law of light with a lightbulb and detector. The lightbulb’s intensity and the detector’s distance can be adjusted to see how they affect the reading. There are two bulbs and detectors to allow side-by-side comparisons.
Reassess and Apply
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