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AQA Physics PHYA5 - Thursday 18th June 2015 [Exam Discussion Thread] Watch

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    (Original post by AR_95)
    So I understand that there's a time delay before the daughter nucleus emits the gamma photon
    The metastate, is when the daughter nucelus is excited and is yet to emit the photon to de excite/ return to ground state?

    Also in my book it mentions this occurs in alpha decay, so why've you only limited it to Beta?
    I believe it occurs in both, the metastate is an excited state for a prolonged period of time
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    (Original post by Sbarron)
    Must we always put neutrino as a product of alpha decay for the marks?
    Do you not mean Beta decay..? and better safe than sorry so just put it in anyway even if it's in brackets.
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    (Original post by betbi3etwerrd)
    Quasars are the most distant and most powerful observable objects.
    Using inverse square law it is shown that they produce the same power output of several galaxies but variation in their output suggests they may be only the size of a solar system.
    They are now believed to come from a super massive black holes at the centre of active galaxies.

    They emit electromagnetic radiation from the whole spectrum.
    Doesn't really answer my question... Are they very small galaxies with black holes in the centre and very bright? Also what would an exam definition of one be?
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    (Original post by AR_95)
    Someone give me a concise definition of the metastable state?
    I think all we need to know is that "a meta stable state is one in which a nucleus can remain in an exited state for a longer than normal time period"
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    (Original post by Sbarron)
    I think I've learned it now although I'm far from full comprehension of it
    If I understand it like that then I will forget it soon


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    (Original post by PotterPhysics)
    Turning points chapter 1: "The emission of light from a discharge tube happens because the voltage applied to the tube is so high that it pulls electrons out of some of the gas atoms in the tube."

    How can a high voltage (edit: by itself) pull off electrons from atoms?
    The voltage applied is a result of potential difference between anode and the cathode plates. Therefore at hight voltage anode becomes significantly positive that can pull electrons out of the atoms since the electrons are attracted to the positive plate.


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    (Original post by Sbarron)
    Must we always put neutrino as a product of alpha decay for the marks?
    in the two books I have, neither have mentioned a neutrino as a product of alpha decay
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    (Original post by slaven123)
    Doesn't really answer my question... Are they very small galaxies with black holes in the centre and very bright? Also what would an exam definition of one be?
    Quasars are controversial, it would be unfortunate if they'd ask for a definition since all we know is that they're very powerful observable objects that are very far away.

    The book says "they are now believed to come from super-massive black holes at the centre of active galaxies" but doesn't say that they're small galaxies with black holes in the centre.
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    (Original post by betbi3etwerrd)
    Do you not meName:  image.jpg
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Size:  516.8 KBan Beta decay..? and better safe than sorry so just put it in anyway even if it's in brackets.
    According to this it's alpha
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    (Original post by Sbarron)
    According to this it's alpha
    Well someone is gonna have to enlighten me because the lepton number doesn't seem to add up.

    Also my CGP book as the exact same reaction but without the neutrino.

    Could I ask what book you're using?
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    (Original post by AR_95)
    in the two books I have, neither have mentioned a neutrino as a product of alpha decay
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    (Original post by betbi3etwerrd)
    Well someone is gonna have to enlighten me because the lepton number doesn't seem to add up.
    The revision guide is wrong for flux linkage too so....
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    My CGP and Nelson Thornes book doesn't mention or agree with neutrinos for Alpha decay.

    Also CGP book has exact same equation but without the neutrino.

    Are you using a really outdated book because this stuff might just be new discoveries or whatever..
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    Yeah guys I watched a video by LAE physics on YouTube today that said some revision guides mistakenly add neutrinos as the product of alpha decay which is plain wrong due to conservation of lepton number.


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    After studying AQA physics I'm not even sure I believe any of these 'invisible' particles exist! I don't think I believe anything anymore!
    Possibly AQA are the illuminati 😱😳
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    (Original post by CD223)
    Yeah guys I watched a video by LAE physics on YouTube today that said some revision guides mistakenly add neutrinos as the product of alpha decay which is plain wrong due to conservation of lepton number.


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    Basically idiots wrote my book!
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    (Original post by betbi3etwerrd)
    Quasars are controversial, it would be unfortunate if they'd ask for a definition since all we know is that they're very powerful observable objects that are very far away.

    The book says "they are now believed to come from super-massive black holes at the centre of active galaxies" but doesn't say that they're small galaxies with black holes in the centre.
    Ahh, Okay. I was wondering why I couldn't find a proper explanation anywhere. A paper I did from the old spec asked 'Explain what is meant by a Quasar' but hopefully it won't come in the new one!
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    (Original post by slaven123)
    Ahh, Okay. I was wondering why I couldn't find a proper explanation anywhere. A paper I did from the old spec asked 'Explain what is meant by a Quasar' but hopefully it won't come in the new one!
    What did the mark scheme say?


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    (Original post by Sbarron)
    After studying AQA physics I'm not even sure I believe any of these 'invisible' particles exist! I don't think I believe anything anymore!
    Possibly AQA are the illuminati 😱😳
    Lol, that's invisible to the eye, not the mind


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    (Original post by CD223)
    What did the mark scheme say?


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    Any two from: very powerful/bright
    radio source
    very distant
    relatively small

    Seems very vague still though... But I guess its because they're controversial like you said.
 
 
 
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