Doppler Effect and Spectroscopy

The Doppler Effect Waves coming from a moving source get their wavelength “smooshed” or “stretched”.

The Doppler Effect Waves have shorter wavelengths and higher frequencies when moving toward us.

The Doppler Effect Waves have longer wavelengths and lower frequencies when moving away from us.

The Doppler Effect The greater the speed of the object, the larger the difference in frequency between the front and the back positions. Examples: The sound of a siren of a fire engine is louder when approaching you then lowers significantly right after it passes. http://www.youtube.com/watch?v=Tn35SB1_NYI https://www.youtube.com/watch?v=Djz_rtnXSfY

Spectroscopy The study of analyzing matter using electromagnetic emission or absorption spectra Emission Spectra: Characteristic set of colored lights emitted by an excited element Caused by the movement of electrons in an atom

Spectroscopy Real-life applications: Identifying composition of distant stars. Identifying unknown compounds at a crime scene Discovering forgeries

Emission Spectrum of Hydrogen Spectral line 1 nm = 1 x 10-9 m = “a billionth of a meter”

Vocab Spectral Line: Spectrometer: Each individual line of color appearing in a spectrometer Spectrometer: A device that spreads light into its different colors

Emission Spectrum of Hydrogen 1 nm = 1 x 10-9 m = “a billionth of a meter” 410 nm 434 nm 486 nm 656 nm

Continuous and Line Spectra Each Element has a unique emission spectrum Light Sodium Hydrogen Calcium Mercury