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# redshift and doppler effect help watch

1. can anyone summarise the key points needed to get the marks in the exam for red shift and the doppler effect
2. They are different for every exam board. For mine (OCR A)
Using the equation
Explaining why this equation works for only light (as it contains c)
Using red-shift to calculate distances to certain objects in space at very large distances

Doppler effect is only mentioned in Doppler scans in my syllabus:
The frequency of a radio-gun receiver for detecting vehicle speeds is given as

This can be used to colour code certain scans in ultrasound, for blood flowing towards and away from the receiver.
3. (Original post by The-Spartan)
They are different for every exam board. For mine (OCR A)
Using the equation
Explaining why this equation works for only light (as it contains c)
Using red-shift to calculate distances to certain objects in space at very large distances

Doppler effect is only mentioned in Doppler scans in my syllabus:
The frequency of a radio-gun receiver for detecting vehicle speeds is given as

This can be used to colour code certain scans in ultrasound, for blood flowing towards and away from the receiver.
Im not going to list them all here, but here is your spec
You will find the points you need on pages 17-19.
can anyone summarise the key points needed to get the marks in the exam for red shift and the doppler effect
Light from distant galaxies is red shifted
Blue shift would indicate galaxy moving towards us
Red shift is proof the universe is expanding
Can be proof for the big bang theory, if the universe is growing bigger this means there must have been an initial starting point for the universe
Doppler effect: when source moves away from the person, wavelength increases and frequency decreases. When source moves towards the person, wavelength decreases and frequency increases.

*EDIT* this is for AQA science btw

Rep me if this is helpful and feel free to ask any more questions
6. (Original post by tamanna___)
Light from distant galaxies is red shifted
Blue shift would indicate galaxy moving towards us
Red shift is proof the universe is expanding
Can be proof for the big bang theory, if the universe is growing bigger this means there must have been an initial starting point for the universe
Doppler effect: when source moves away from the person, wavelength increases and frequency decreases. When source moves towards the person, wavelength decreases and frequency increases.

*EDIT* this is for AQA science btw

Rep me if this is helpful and feel free to ask any more questions
Thanks.Tried looking in the GCP book higher however it just confused me because this is what it says:"Different chemical elements absorb different frequencies of light.Each element produces a specific pattern of dark lines at the frequencies that it absorbs in the visible spectrum"
could u try make sense of this for me.Thank u
Thanks.Tried looking in the GCP book higher however it just confused me because this is what it says:"Different chemical elements absorb different frequencies of light.Each element produces a specific pattern of dark lines at the frequencies that it absorbs in the visible spectrum"
could u try make sense of this for me.Thank u
A chemical element can absorb a specific 'quanta' of light. This energy has a very specific value based on what the electrons need to jump up 'energy levels'.
This specific energy corresponds to a very specific frequency of light.
Where h is the planck constant
After it is absorbed, the electrons jump back down energy levels and so re-emit this energy as light of the specific frequency that it absorbed to move up energy levels.
Thanks.Tried looking in the GCP book higher however it just confused me because this is what it says:"Different chemical elements absorb different frequencies of light.Each element produces a specific pattern of dark lines at the frequencies that it absorbs in the visible spectrum"
could u try make sense of this for me.Thank u
So basically, you know about the electromagnetic spectrum right, if a wavelength is increased then light shifts to the red side and vice verse if wavelength decreases. So about the dark lines, what you need to know is "We are able to see the effects of red and blue shift by observing dark lines in the spectra fom galaxies"
(Spectra is the electromagnetic spectrum)
Now so say theres a galaxy moving far away from us, how can scientists be so sure that it is moving? Well they observe the spectrum of colours that the galaxy is giving off, and they look to see where the dark lines are placed (literal dark black lines) if the galaxy is moving away the dark lines will be more towards the red end and if it is moving towards us there will be dark lines towards the blue side.
9. (Original post by tamanna___)
So basically, you know about the electromagnetic spectrum right, if a wavelength is increased then light shifts to the red side and vice verse if wavelength decreases. So about the dark lines, what you need to know is "We are able to see the effects of red and blue shift by observing dark lines in the spectra fom galaxies"
(Spectra is the electromagnetic spectrum)
Now so say theres a galaxy moving far away from us, how can scientists be so sure that it is moving? Well they observe the spectrum of colours that the galaxy is giving off, and they look to see where the dark lines are placed (literal dark black lines) if the galaxy is moving away the dark lines will be more towards the red end and if it is moving towards us there will be dark lines towards the blue side.
10. Red shift: source moves away from observer --> wavelength increases so frequency decreases and colours shift to red end of the spectrum
Blue shift: source moves towards observer --> wavelength decreases so frequency increases and colours shift to blue end of the spectrum

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