Natural Science - Year II
Unit 49: Thomas Young and Light
Science Web Assignment for Unit 49
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Science Lecture for Unit 49: Light
For Class
- Topic area: Physics: Light, waves
- Terms and concepts to know: waves, particles, spectrum, microwaves, infrared, visible light, ultraviolet, x-rays, photons.
- See historical period(s): 1880-1920
Outline/Summary
Light
Several centuries of experiments on the nature of light still leave us with many puzzles. Light behaves like a wave when it travels through a medium, but it behaves like a series of small packets of energy (photons) when it interacts with matter. We can sense electromagnetic radiation with our eyes (visible light), with our skin (which sunburns in UV light) and with all of our body (feeling infrared light as heat). It is simple to say light is a form of energy, but difficult to show how light energy manifests itself in many different phenomena, including reflection and refraction through media like glass lenses, and as different frequencies through filters.
The following readings ask you to examine only a few of the key characteristics of light.
Take a look at the Readings on Light and Optics at the Patterns in Nature site. There are a number of different pages, and you may need to look at several in order to answer the following questions. [This is an archive of a discontinued website, and some images may be missing.]
- What are wavelength, frequency, and amplitude? [The Path of Light]
- How is light reflected from a surface? [The Reflection of Light]
- How is light refracted through a medium? [The Refraction of Light]
- What is the light spectrum? [Color and Light]
- How much of the electromagnetic spectrum do we see? [Color and Light]
- What is polarized light? [Polarized Light]
Study the discussion of the dual nature of light based on the Nobel prize archives.
- What is the evidence for the "particle nature" of light?
- What is the evidence for the "wave nature" of light?
Study/Discussion Questions
- What phenomena led Einstein to assume that the photoelectric effect could be explained by think of light as photons?
- How does the amount of energy in a light wave change with color?
- How does the fact that we need two theories to explain how light works challenge our ideas of how science describes nature?
Further Study On your Own (Optional)
- There is a good summary of the terms associated with theories of light in the hypertext physics book.
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