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    Question:

    Electronic photographic flash guns usually involve a capacitor being charged to a relatively high voltage, then discharged through a flash tube containing a very small quantity of xenon gas.

    If a discharge is to produce a flash equivalent to a 1000W bulb lit for 1ms, calculate the voltage to which a 100 micro F (10-6) capacitor should be charged.

    State any assumptions you have made.

    ................................ ...........................

    I would appreciate any ideas. I'm currently working on a few methods but as of yet haven't reached a satisfactory answer. Cheers.

    Please explain any workings you use to get your answers
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    You can calculate the energy using E = Pt = 1000*1*10^-3

    You can then use E = (1/2)CV^2 to calculate the voltage across the capacitor. Rearrange in terms of V and then substitute your value for E in.
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    (Original post by Nylex)
    You can calculate the energy using E = Pt = 1000*1*10^-3

    You can then use E = (1/2)CV^2 to calculate the voltage across the capacitor. Rearrange in terms of V and then substitute your value for E in.
    ahh....cunning - cheers
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    (Original post by need_help)
    ahh....cunning - cheers
    No prob. Assumptions: I think you say you're assuming that exactly half of the energy stored in the capacitor is used to produce the flash, the other half will be wasted. Not 100% sure on that though.
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    (Original post by Nylex)
    No prob. Assumptions: I think you say you're assuming that exactly half of the energy stored in the capacitor is used to produce the flash, the other half will be wasted. Not 100% sure on that though.
    no, i think this last bit is wrong. you are assuming that 100% of the energy stored in the capacitor is used to produce the flash. in reality this ofcourse is wrong as energy is lost as heat, sound (a bit) etc.
 
 
 
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