Paper 2 - Astrophysics

Question 1

How can the brightness of a star at a standard distance be represented using absolute magnitude?

Answer 1

The lower the value of absolute magnitude, the brighter the star (and vice versa)

Question 2

Describe the past evolution of the universe and the main arguments in favour of the Big Bang Theory

Answer 2

• Measurements of the rede-shift suggest that all the distant galaxies are moving away from Earth quickly
• More distance galaxies have greater red-shifts than nearer ones - they show a bigger observed increase in wavelength
• The more distant galaxies are moving away faster than the nearer ones
• Therefore the universe is expanding which was started by a huge explosion - The Big Bang

Question 3

Describe evidence that supports the Big Bang Theory

Answer 3

• The more distant galaxies are moving away faster than the nearer ones
• Therefore the universe is expanding which was started by a huge explosion - The Big Bang
• There is a detectable cosmic microwave background radiation (CMBR) detectable in all parts of the universe
• This is thought to have been left over from The Big Bang

Question 4

Describe how if a wave source is moving relative to an observer, there will be
a change in the observed frequency and wavelength

Answer 4

• Infront of the source, the wavelength decreases and the frequency increases
• Behind the source, the wavelength increases and the frequency decreases

Question 5

Describe the red shift in light received from galaxies at different distances
away from the Earth

Answer 5

• If a light source moves away from an observer, the wavelength of the emitted light increases
• Therefore the light appears to shift to the red end of the electromagnetic spectrum