Integrated Coordinated Science for the 21st Century
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Answers
Physics To Go
- a) Neon signs will show line spectra.
b) The light that makes a saturated color has only a limited range of wavelengths. Parts of its spectrum would be dark. The light that makes an unsaturated color contains white. It would have a continuous spectrum as a background to the range of wavelengths that define its color.
- We could send an image, perhaps on a plaque, that shows the spacing of hydrogen lines (hydrogen is the most common element in the universe). Providing the spacing of the carbon lines could suggest that we are a carbon-based life form. We might be able to communicate the fact that our eyes respond to the wavelengths of (visible) light.
- a) Perhaps the signal would be sent at the frequency of a spectral line of an important element, like hydrogen. We could search at that frequency.
b) Since the chemical elements ought to be the same throughout the universe, and a technological civilization would understand spectra, the spectra information can be a common language.
- a) Spectral lines can be detected and measured with detectors that are sensitive to the infrared or ultraviolet.
b) Perhaps visible lines, since that it what we can sense; or perhaps we could find a spectral line at a microwave frequency, since microwaves penetrate space particularly well.
c) The life form might be able to sense infrared.
- The spectra could be used to identify toxins in food samples, or dangerous chemicals in a sample of river water, or drugs in the blood of an unconscious person.
- a) Students will probably say that the law should be changed so that food with harmless trace amounts of substances can be sold.
b) Answers will vary.
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