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    Im worried about this exam because I'm doing triple science at A level and have to get A* in all my science exams
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    What are the advantages and disadvantages for Ct scanner,ultrasound and x-rays? Couldn't find them anywhere
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    PHYSICS is my worst science out of all of them....

    I AM REALLY HOPING I GET AN A...my gawdddd
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    (Original post by Lauren-x-)
    My predictions for 5/6 markers (I haven't done a couple of papers yet so I may change it once I've done them)

    P2: Hooke's law experiment, star formation, car safety (I wish)

    P3: centre of mass experiment or motor effect maybe?

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    How would they make a six marker on hookes law?!
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    (Original post by kassy12324)
    What are the advantages and disadvantages for Ct scanner,ultrasound and x-rays? Couldn't find them anywhere
    CT Scanner-
    ads: can produce 3D images, can distinguish between different tissue types as well as bone vs soft tissue
    disads: greater radiation dose (ionising) and more expensive than normal x-rays

    X-Rays-
    ads: can distinguish between bone and soft tissue (can see a broken bone eg.), fairly cheap
    disads: ionisation could damage cells, image doesn't distinguish between different soft tissue, image is 2D

    Ultrasound-
    ads: non-ionising so much safer, can distinguish between soft tissue types, a real-time 'video' is produced
    disads: don't really know sorry!!

    If if anyone knows disadvantages of ultrasound that would be very helpful and if anyone can add anything too!! 😄😄
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    (Original post by AvKar)
    CT Scanner-
    ads: can produce 3D images, can distinguish between different tissue types as well as bone vs soft tissue
    disads: greater radiation dose (ionising) and more expensive than normal x-rays

    X-Rays-
    ads: can distinguish between bone and soft tissue (can see a broken bone eg.), fairly cheap
    disads: ionisation could damage cells, image doesn't distinguish between different soft tissue, image is 2D

    Ultrasound-
    ads: non-ionising so much safer, can distinguish between soft tissue types, a real-time 'video' is produced
    disads: don't really know sorry!!

    If if anyone knows disadvantages of ultrasound that would be very helpful and if anyone can add anything too!! 😄😄
    Thanks so much 😄
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    (Original post by kassy12324)
    Thanks so much 😄
    There aren't many disadvantages of ultrasound, but there's one:

    Ultrasound does not reflect clearly from bone or air thus giving it limitations. For images of the lungs and bones other techniques are clearer and therefore preferred.
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    How is revision going?


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    (Original post by SSAA9)
    How is revision going?


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    Please don't 😐
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    (Original post by SSAA9)
    How is revision going?


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    Okayish; I did like 5hours physics today including 2 past papers! I think one of the hardest things is remembering really small details! Ag least the exam is in the afternoon
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    We're still at school because we don't have study leave until Friday so I've hardly done any revision 😔
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    (Original post by physicsamor)
    Learn the circuit diagrams to draw a circuit, firstly.
    Rules:
    Ammeter must always be places in series (even in a parallel circuit), as well as the component under test and the variable resistor (if your using one) (also you need to know what a thermistor, ammeter, voltmeter, diode and variable resistor do, because they could be up to a 3 mark question on them)
    Voltmeter must be always be placed in parallel, parallel to the component under test.
    Series
    Different components are connected in a line, end to end between the +ve and ve- in a series circuit.
    1. Potential difference is shared: the voltages round a series circuit add up to equal the source voltage.
    V= V1 =+ V2
    2) Current is the same everywhere
    A1=A2
    3) Resistance adds up
    R= R1 + R2 + R3
    4) Cell voltages add up
    potential difference when more cells are in series is bigger, if the cells are all connected in the same way.
    2) E.g two batteries of voltage 1.5 V are connected in series so they suply 3V between them.
    Parallel
    1. P.D is the same across all components.
    V1= V2=V3
    2. Current is shared between branches
    A= A1+A2+A3
    Attachment 399083 try this question (basic I know)
    Thank you so much for this, i really appreciate it! I'll have a go at the question now.
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    What are the precautions taken for an x-ray?
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    (Original post by kassy12324)
    What are the precautions taken for an x-ray?


    • Use lead absorber plates (isolate the area to be investigated)
    • Wear lead vests or stand behind a lead screen (if you aren't the patient)
    • Keep exposure time to a minimum
    • People working with x-Rays should wear a film badge (it shows overexposure)
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    (Original post by AvKar)
    • Use lead absorber plates (isolate the area to be investigated)
    • Wear lead vests or stand behind a lead screen (if you aren't the patient)
    • Keep exposure time to a minimum
    • People working with x-Rays should wear a film badge (it shows overexposure)
    Thanks so much, helped a lot 😄
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    I think physics unit 3 will be extremely hard because so far I feel the biology and chemistry have been really easy and nice :s
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    could someone please explain earthing to me in the most simple way possible? never quite understand it
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    (Original post by hope99)
    Thank you so much for this, i really appreciate it! I'll have a go at the question now.
    No Problem
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    (Original post by hikmbuj)
    could someone please explain earthing to me in the most simple way possible? never quite understand it
    Earthing
    Sometimes a fault can develop when the live wire touches the metal case, then because the metal case is earthed, a surge of current flows in through the live wire, through the case. The metal case being earthed diverts the current to the earth wire, through the earth wire to the ground/earth, meaning that a big current has flowed to earth. The big surge in current melts the fuse (As the amount of current will be greater than the fuse ratings). This cuts off the live supply and breaks the circuit, which isolates the appliance from the the live, making it impossible to get an electric shock from the case, thus preventing the risk of fire caused by the heating effect of a large current.
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    Everyone excited for physics?!
 
 
 

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