OCR Physics A G485 - Frontiers of Physics - 18th June 2015 Watch

SkilledNChilled
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#1021
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#1021
(Original post by actanide)
the equation of (change of lambda/lab lambda) = (velocity/speed of light) one, and probably the v=(lambda * frequency) one from last year
I presume this works for both if the source is moving and when the observer is moving? Also thanks.
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randlemcmurphy
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#1022
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#1022
This may be a really silly question but if the age of the universe is 1/H0, and H0 is a constant (the gradient of v/x graph) then how can the age of the universe ever change?
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L'Evil Fish
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#1023
(Original post by randlemcmurphy)
This may be a really silly question but if the age of the universe is 1/H0, and H0 is a constant (the gradient of v/x graph) then how can the age of the universe ever change?
Because it isn't accurate

Galaxies will be around the line, not exactly on it

It's a line of best fit so, H0 is approximate
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actanide
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#1024
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#1024
(Original post by SkilledNChilled)
I presume this works for both if the source is moving and when the observer is moving? Also thanks.
I think you are making this way too complicated than it should be technically speaking, our Galaxy is moving through universe just as other Galaxies are. Its about the change of the wavelenght between the one we observe here on earth and the one from distant galaxies. So yeah, both source and objects can be moving, but for the simplicity, you say that the receiver stays still and there is a change in wavelenght/frequency of the source
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actanide
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#1025
Anyone done the specimen paper? I need help in question 4, I have no idea how to draw the graph of induced EMF.

Hate graphs.
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Engineering Lad
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#1026
(Original post by randlemcmurphy)
This may be a really silly question but if the age of the universe is 1/H0, and H0 is a constant (the gradient of v/x graph) then how can the age of the universe ever change?
H0 is said to be constant, but really it should be called the 'Hubble nearly constant', since it's value is so uncertain. It's supposedly between 50 and 100 km/s/Mpc and normally we use a value of 70, which gives an age of approximately 13.7 billion years. This value changes depending on the value of H0 used within the given range.
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Raizel
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#1027
https://86702370e68cc0f4d10e729b4f36...%20A-level.pdf

6bii part 1
can someone explain to me the reason of that method of calculation to achieve the answer.
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actanide
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SkilledNChilled
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(Original post by actanide)
I think you are making this way too complicated than it should be technically speaking, our Galaxy is moving through universe just as other Galaxies are. Its about the change of the wavelenght between the one we observe here on earth and the one from distant galaxies. So yeah, both source and objects can be moving, but for the simplicity, you say that the receiver stays still and there is a change in wavelenght/frequency of the source
Thanks!
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Elcor
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#1030
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#1030
I was way more prepared for G484 which makes absolutely no sense
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ETRC
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(Original post by actanide)
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that was the most stupid question ever
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xy0mz
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#1032
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#1032
Could someone pls explain 9.(c) in June14, preferably with a diagram? Cheers.Name:  ImageUploadedByStudent Room1434540632.795327.jpg
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Elcor
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#1033
Was a complete waste of my time going into school
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sagar448
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#1034
There are two medical tracers, technetium and FDG-18. I know FDG is used for PET but what is the technetium used for? Please help.
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actanide
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(Original post by ETRC)
that was the most stupid question ever
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Alex621
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#1036
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(Original post by Elcor)
Was a complete waste of my time going into school
My teacher tried to make me go in today and he said 'we'll go through a past paper' and i told him i would go but i didn't bother in the end. I need to do all the past papers today and the time it would take me to get there didn't seem worth it especially considering we would probably spend the whole day on just one paper.
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actanide
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(Original post by sagar448)
There are two medical tracers, technetium and FDG-18. I know FDG is used for PET but what is the technetium used for? Please help.
technetium is very transferrable around the body, mixed with glucose and other substances. It can be used to detect if a kidney is healthy. It goes through the kidney the same as water etc, and if the kidney is faulty, itll give off bigger radiation from that area, meaning the kidney doesnt pass liquids well
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Elcor
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(Original post by actanide)
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no it should be like a digital wave i.e. 2 horizontal lines

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actanide
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#1039
(Original post by Elcor)
no it should be like a digital wave i.e. 2 horizontal lines

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Elcor
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(Original post by actanide)
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Yeah connected

It's because the rate of change of flux linkage is constant as the coil is moving at a constant velocity - hence constant e.m.f. induced

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