DOPPLER EFFECT

FOR YOUR NOTEBOOK:

Notes and Key Terms

• Doppler Effect - The apparent change in wavelength or frequency of the radiation from a source due to its relative motion away from or toward the observer.

• There is no actual change in the frequency of the wave, the effect is observed because of a change in the distance between the source and the observer.

• The Doppler effect can be observed for any type of wave (water, sound, light)

• In astronomy, the Doppler effect is used to examine shifts in frequency of electromagnetic waves

  • This is what helps us determine the movement of stars and galaxies.

  • Downward shift- when a star is moving away from Earth (red shift)

    • Due to an increase in wavelength this movement appears red (~700 nm)

  • Upward shift- when a star is moving toward Earth (blue shift)

    • Due to a decrease in wavelength this movement appears blue (~450 nm)