Final Exam: Sun 2 Flashcards
What is the Doppler effect?
You hear the Doppler effect every time a car or truck passes you, and the pitch of its engine noise or emergency siren seems to drop
Sound is shifted in shorter wavelengths and higher pitches while it is approaching.
Sound is shifted to longer wavelengths and lower pitches after it passes by
How does the Doppler effect apply to stars?
Star 1 is moving directly away from us, so the Doppler shift tells us it’s full speed
Star 2 is moving across our line of sight, but not toward or away from us. Doppler shift measures no speed at all
Star 3 is moving diagonally away from us. Doppler shift measures only the part of its speed directly away from us
Doppler effect question
I measure a line in the lab at 500.7 nm
The same line in a star has wavelength 502.8
What can I say about the star?
A) it is moving away from me
B) it is moving towards me
C) it had unusually long spectral lines
Answer is A
Doppler effect summary, flip card
Motion towards or away from an observer caused a shift in the observed wavelength of light:
Blueshift (shorter wavelength) -> motion towards you
Redshift (longer wavelength) -> motion away from you
Greater shift -> greater speed
