What is the Doppler Effect?
The change in frequency or wavelength of a wave in relation to an observer moving relative to the wave source.
How does the Doppler Effect manifest with sound waves?
As a vehicle approaches, the pitch of the sound increases; as it moves away, the pitch decreases.
What happens to sound waves when a source moves towards an observer?
The waves bunch up, increasing frequency and decreasing wavelength.
What happens to sound waves when a source moves away from an observer?
The waves stretch out, decreasing frequency and increasing wavelength.
What is the formula for calculating observed frequency in the Doppler Effect?
fo = fs (v ± vs) / (v ± vo), where fo is observed frequency, fs is source frequency, v is wave velocity, vs is source velocity, and vo is observer velocity.
What does the ‘+’ sign indicate in the Doppler Effect formula?
It indicates that the source is moving away from the observer.
What does the ‘−’ sign indicate in the Doppler Effect formula?
It indicates that the source is moving towards the observer.
What is redshift in the context of astronomy?
The increase in wavelength of light from a star moving away from an observer.
What is blueshift?
The decrease in wavelength of light from a star moving towards an observer.
How can redshift be calculated?
Using the formula z = v/c, where z is redshift, v is the velocity of the star, and c is the speed of light.
What is the relationship between redshift and the motion of a star?
Redshift is positive if the star is moving away and negative if it is moving towards the observer.
What is Hubble’s Law?
The observation that the recessional velocity of galaxies is proportional to their distance from us.
What does Hubble’s Law formula express?
v = H0d, where v is the relative velocity of a star, H0 is the Hubble constant, and d is the distance to the star.
What does a greater redshift indicate about a galaxy?
It indicates that the galaxy is moving away from us at a higher speed.
What is the significance of the Hubble constant?
It quantifies the rate of expansion of the universe.
How did Edwin Hubble contribute to our understanding of the universe?
He discovered that the universe is expanding and that the speed of galaxies moving away depends on their distance.
What is the observed wavelength formula for calculating redshift?
z = (λobserved - λrest) / λrest, where λobserved is the observed wavelength and λrest is the wavelength emitted by the star.
What does a redshifted spectrum indicate?
It indicates that the light from the star has shifted towards longer wavelengths due to the star moving away.
What does the term ‘absorption spectra’ refer to?
The patterns of light absorption by elements in a star’s atmosphere, which can show redshift.
What is the relationship between distance and recessional velocity according to Hubble’s observations?
The further away a galaxy is, the faster it is receding from us.
What is the relationship between the distance of a star from Earth and its recessional velocity?
The further the star is from Earth, the greater the velocity it is moving away from us.
What theory explains the expansion of space and the age of the universe?
The Big Bang Theory.
What is the estimated age of the universe?
About 13 to 14 billion years.
What is the maximum width of the observable universe?
46 to 47 billion light years.
