D

Question 1

Doppler effect

Answer 1

The Doppler effect is the apparent change in
frequency (or wavelength) of the wave caused
by the relative motion between the source of
the wave and the observer:
Lecture 18 –
Doppler Effect
– When the relative speed of the source and observer is
higher than the speed of the wave, the frequency appears to
increase
– When the relative speed of the source and observer is lower
than the speed of the wave, the frequency appears to
decrease

Question 2

Red shift

Answer 2

Red shift: the wavelength will appear longer. (doesn’t mean
light is red!)
Notice the color of the moving galaxy doesn’t change to red or
blue!
Galaxy receding (moving away from Earth), spectral line shifts
towards the blue (shorter wavelength)

Question 3

Blue shift

Answer 3

Blue shift: the wavelength will appear shorter. (but light does
not turn blue!)
Notice the color of the moving galaxy doesn’t change to red or
blue!
Galaxy approaching (moving towards Earth), spectral line shifts
towards the blue (shorter wavelength)

Question 4

Peak trequency or wave enoth continuous
spectra only)

Answer 4

Temperature (Wien’s law)

Question 5

Lines present

Answer 5

Composition, temperature

Question 6

Lines intensities

Answer 6

Composition, temperature

Question 7

Line width

Answer 7

Temperature, turbulence, rotation speed, density and magnetic field