Space physics - Red shift

Question 1

What happens to wave crests when the wave source is moving?

Answer 1

The crests bunch together in front of the source, decreasing the wavelength. Behind the source, the waves spread out, increasing the wavelength.

Question 2

How does this affect the sound of a siren from a moving emergency vehicle?

Answer 2

As it approaches, the siren has a higher pitch (shorter wavelength). As it moves away, the pitch sounds lower (longer wavelength). This is known as the Doppler effect.

Question 3

How does the Doppler effect apply to light?

Answer 3

When light from a moving source has:
A shorter wavelength, the source is moving towards us → this is called blue-shift
A longer wavelength, the source is moving away from us → this is called red-shift

Question 4

whats blue shift

Answer 4

A shorter wavelength, the source is moving towards us

Question 5

whats red shift

Answer 5

A longer wavelength, the source is moving away from us

Question 6

whats red shift CCEA answer

Answer 6

is the increase in the wave length of light from the distant galaxies due to their increasing separation from us

Question 7

How do physicists describe visible light?

Answer 7

As a continuous spectrum from red to violet with an infinite number of colours, each associated with a specific wavelength

Question 8

How do we know the Sun contains hydrogen

Answer 8

The light spectrum from the Sun shows Fraunhofer lines, which are black lines caused by hydrogen atoms absorbing certain wavelengths. This pattern is known as the absorption spectrum for hydrogen.

Question 9

What do we observe when looking at the light from distant galaxies?

Answer 9

What do we observe when looking at the light from distant galaxies?

Question 10

What does this red shift in light from distant galaxies indicate

Answer 10

it shows that the galaxies are moving away from us.

Question 11

What conclusion can be drawn from the fact that galaxies are moving away?

Answer 11

the Universe is expanding, meaning the distance between galaxies is constantly increasing.

Question 12

How does this support our understanding of the origin of the Universe?

Answer 12

the expansion of the Universe supports the Big Bang theory, which proposes that the Universe began from a single point and has been expanding ever since.