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    Ok so i'm revising the photoelectric effect for AS physics and im struggling with the equations.

    The question i need to answer is:

    A gold surface is illuminated with monochromatic ultra violet light of frequency 2.10 x 12^15 Hz. The maximum kinetic energy of the emitted photo electron is 6.20 x 10^19 J. Calculate

    a) the energy in J of the incident photon
    b) the work function of gold

    So for a i do E=hf which gives me a total of 1.39 x 10^50 ?? am i way off?

    so then i used the photo electric equation hf=Ekmax + phi and i took the max kinetic energy away from hf to leave me with the work function??

    Sorry if that makes no sense, any help would be greatly appreciated :confused:
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    (Original post by lornielou2012)
    Ok so i'm revising the photoelectric effect for AS physics and im struggling with the equations.

    The question i need to answer is:

    A gold surface is illuminated with monochromatic ultra violet light of frequency 2.10 x 12^15 Hz. The maximum kinetic energy of the emitted photo electron is 6.20 x 10^19 J. Calculate

    a) the energy in J of the incident photon
    b) the work function of gold

    So for a i do E=hf which gives me a total of 1.39 x 10^50 ?? am i way off?

    so then i used the photo electric equation hf=Ekmax + phi and i took the max kinetic energy away from hf to leave me with the work function??

    Sorry if that makes no sense, any help would be greatly appreciated :confused:
    that would be a heck of an energetic photon.
    You've got the right formula but something has gone wrong in the calculation.
    Also 2.10*12^15 is a non standard way of expressing a number, are you sure you copied that right?
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    Thats what I thought!

    it should be (6.63 x 10-34) X (2.10 X 1015)

    And i've just spotted my mistake! i think the answer should be 1.39x10-18

    Have i done the right thing to find the work function?

    Thanks for your reply!
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    You're right.
    Obv it's good skills to be able to spot when an answer is unreasonable and re check your calculation in exams.

    Fwiw 10^12 electron volts is a high energy for a 'lab made' particle (if you have a £multi-million accelerator), and an electron volt is of course a far smaller unit than a joule.
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    (Original post by Joinedup)
    You're right.
    Obv it's good skills to be able to spot when an answer is unreasonable and re check your calculation in exams.

    Fwiw 10^12 electron volts is a high energy for a 'lab made' particle (if you have a £multi-million accelerator), and an electron volt is of course a far smaller unit than a joule.
    10^12 eV is only a factor of 7 away from the highest energy collisions ever achieved in ANY particle accelerator including the £multi-billion ones!
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    (Original post by uberteknik)
    10^12 eV is only a factor of 7 away from the highest energy collisions ever achieved in ANY particle accelerator including the £multi-billion ones!
    I can remember that the tevatron was named for being a Tera (10^12) electron volt collider and we're still not an order of magnitude higher.
    It'd seem strange if a cheapo uv lamp was making more energetic particles than that.
 
 
 
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