IB Physics SL C.5.3 Light Doppler approximation
IB Physics SL C.5.3 Light Doppler approximation
Use the light Doppler approximation to calculate speeds from spectral shifts and decide from wavelength data whether motion is towards or away.
How this is tested
- use v/c = Δλ/λ with spectral data, converting nm to m only if needed and keeping speed units consistent
- decide from the sign of Δλ whether the line is redshifted or blueshifted and state motion relative to Earth
- combine Δλ/λ = v/c with v = 2πR/T to calculate an orbital period from a measured spectral shift