SP5d Red shift

Question 1

Doppler effect?

Answer 1

the observed frequency of a wave depends on the relative speed of the source and the observer.

Question 2

Describe the amount of red shift observed in galaxies at different distances from Earth.

Answer 2

In the absorption spectrum of light from stars and galaxies are black lines. If the star or galaxy is moving away from us those lines are red shifted. The bigger the shift, the further away it is, and the faster it is moving, relative to us. We say it is receding.

Question 3

Explain why the red shift of galaxies provides evidence that the universe is expanding.

Answer 3

.Redshift appeared to be greater for faint, presumably further galaxies. So the farther a galaxy, the faster it is receding from Earth
.If all galaxies are moving away from each other and it is the same result no matter in which direction you look, the conclusion is the whole universe is expanding