Doppler effect

• What is the Doppler effect?

  Change in frequency due to motion
• Why does a paramedic in the ambulance not hear a change in the siren's sound?

  They move at the same speed as the ambulance
• How does the frequency of sound waves change for a stationary observer as an ambulance approaches?

  The frequency increases as it approaches
• What happens to the wavelength of sound waves as the ambulance approaches?

  The wavelength decreases as it approaches
• What happens to the frequency of sound waves after the ambulance passes?

  The frequency decreases after it passes
• What happens to the wavelength of sound waves after the ambulance passes?

  The wavelength increases after it passes
• What type of waves does the Doppler effect apply to?

  Both sound and light waves
• What is the emission spectrum of hydrogen in the Sun?

  It produces four specific wavelengths of light
• What happens to the emission spectrum of hydrogen in distant galaxies?

  It is redshifted, moving towards red
• What does redshift indicate about the movement of galaxies?

  They are moving away from us
• What does an increase in redshift imply about distant galaxies?


  They are moving faster away from us
• Who first observed the redshift of galaxies?

  Edwin Hubble
• What theory did Edwin Hubble's observations lead to?

  The Big Bang theory
• What is cosmic microwave background radiation (CMB)?

  Radiation from the edge of the universe
• What does the uniformity of CMB suggest about the universe?

  The universe is still cooling down
• How does CMB relate to the Big Bang theory?

  It supports the idea of a cooling universe
• What is the significance of redshift in astronomy?

  It indicates the movement of galaxies
• What can sensitive equipment measure in distant galaxies?

  Small redshifts in light wavelengths
• How does the speed of galaxies relate to their distance from us?

  Further galaxies move faster away from us
• What does the term "redshift" specifically refer to?

  The stretching of wavelengths of light
• What is the relationship between frequency and wavelength in the Doppler effect?

  Increased frequency results in decreased wavelength
• What is the primary evidence for the Big Bang theory?

  Redshift of distant galaxies
• What does the term "CMB" stand for?

  Cosmic Microwave Background radiation
• What does the uniformity of CMB radiation suggest about the universe's early state?

  It was hot and dense after the Big Bang
• How does the concept of redshift help in understanding the expansion of the universe?

  It shows galaxies are moving apart over time