1. Doppler Effect and Spectroscopy

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

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

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

5. 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.

6. 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

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

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

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

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

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