Doppler Effect - San Francisco State...
Transcript of Doppler Effect - San Francisco State...
Doppler Effect
Doppler Effect
Proper motion can be measured by observing a star’s location for several years.
Radial velocity is usually measured using the Doppler effect.
Δλ
Δλ
~
Shane 3meterTelescope,Mt. Hamilton
CCD LightDetector
DiffractionGrating
Collimator
StarlightFrom Telescope
Keck ObservatoryHigh Resolution Spectrometer
Doppler Effect makes spectral lines shift
Doppler Effect makes spectral lines shift
Doppler shift exaggerated 374,000 times!
Spectrum of Hydrogen
These numbers have a pattern:
Eq on board
They are the wavelengths (in nm) of the spectral lines of Hydrogen.
Spectrum of Hydrogen
Observations of Hydrogen in a lab show it gives off light of specific wavelengths, given by the empirical formula:
...where n & m are integers & RH = 1.1 x 107 m-1
Eq on board
Electron ‘orbits’ nucleus under the electrical force, F, & potential energy, U
Assuming uniform circular motion:
Hydrogen Atom in Classical Physics
Newton’s 2nd Law, (F = m a), gives expressions for: -kinetic energy of the electron. -total energy
But the emission line spectrum of Hydrogen is still not explained....