Dismiss Notice
Join Physics Forums Today!
The friendliest, high quality science and math community on the planet! Everyone who loves science is here!

Homework Help: Watt conversion question

  1. Jul 10, 2006 #1
    The electronic flash attachment for a camera contains a capacitor for storing the energy used to produce the flash. In one such unit, the potential difference between the plates of a 765 µF capacitor is 345 V.

    (a) Determine the energy that is used to produce the flash in this unit.

    Using the formula:
    Energy = .5C(V^2) i found the energy to be 45.527 J

    (b) Assuming that the flash lasts for 5.0 10-3 s, find the effective power or "wattage" of the flash.

    I can not find a formula to convert the given information into wattage however.
  2. jcsd
  3. Jul 10, 2006 #2
    i'd calculate the energy difference on the capacitor (before and after the flash) and devide it by the time of the flash...
  4. Jul 10, 2006 #3
    The defenition of power is the change in energy per unit time. Can you do the problem now?
  5. Jul 10, 2006 #4
    how do i know what the energy is before and after the flash? Would it be that energy before then 0 after?
  6. Jul 10, 2006 #5
    ok, i undersstand know. I take the energy I found and simply divide it by the time passed. Thank you.
Share this great discussion with others via Reddit, Google+, Twitter, or Facebook