Lecture 31

Readings

http://umdberg.pbworks.com/w/page/117089634/Summing%20different%20wavelengths%20--%20spectral%20analysis

http://umdberg.pbworks.com/w/page/125351270/Workout%3A%20Spectral%20analysis

Multiple Wavelengths = Multiple Frequncies

http://hyperphysics.phy-astr.gsu.edu/hbase/Waves/string.html

• Since $v=\lambda \ast f$$v = \lambda * f$ , and $v$$v$ is pretty much fixed for a particular medium/type of wave

  • ( medium = air , water , vacuum , string ) = the material the wave is traveling in/through/on )

• A different $\lambda$$\lambda$ means a different $f$$f$

• So "summing wavelength" really means "summing frequencies"

• We are used to viewing signal as a function of time:

  

• But we can also view them as functions of frequency:

Chemicals

• Absorption Spectrum:

  • Produced when white light is shone through a tube of gas which absorbs some of the light
  • Dip occurs when frequency is absorbed by chemical

• Emission Spectrum:

  • Produces when a hot gas glows giving off light
  • Peak occurs when wave is emitted by chemical