The video tutorial explains the Doppler Effect, which is the change in wavelength of a wave when the source moves relative to the observer. It discusses how the Doppler Effect is observed in everyday life with sound, such as the change in pitch of an ambulance siren as it moves past an observer. The tutorial also covers the Doppler Effect with light, known as redshift, where light from moving sources shifts towards the red end of the spectrum. This redshift observation in distant galaxies supports the Big Bang Theory, suggesting that the universe is expanding. Since 1998, observations indicate that distant galaxies are receding faster than previously thought.

What happens to the pitch of a sound when the source moves away from the observer?

• The pitch remains the same

• The pitch fluctuates

• The pitch decreases

• The pitch increases

Which phenomenon is observed when light from a moving source shifts towards the red end of the spectrum?

• Green shift

• Yellow shift

• Blueshift

• Redshift

What is required for redshift to be observed in light from a moving source?

• The source must be stationary

• The source must be moving at a very high speed

• The source must be moving slowly

• The source must be moving in a circular path

What does the observation of redshift in distant galaxies suggest about the universe?

• The universe is shrinking

• The universe is expanding

• The universe is static

• The universe is contracting

Since 1998, what have observations of supernovae suggested about the movement of distant galaxies?

• They have stopped moving

• They are receding faster than previously thought

• They are moving at the same speed

• They are moving slower than before