Results 1 to 2 of 2

Math Help - how much charge and energy

  1. #1
    Super Member bigwave's Avatar
    Joined
    Nov 2009
    From
    honolulu
    Posts
    580

    Cool how much charge and energy

    1. A rechargeable flashlight battery is capable of delivering 85mA for about 12h.
    How much charge can it release at that rate?

    well i think I did this right.... what ?? me was the time given as h so looks this has to be converted to s (seconds) to do this. is this always the case?

    Q=\int_0^{12x60x60} (85x10^{-3})dt = 3672\rightarrow3.672kC

    2. If its terminal voltage is 1.2V, how much energy can the battery deliver.

    so on this one I just multiplied the voltage to the current

    W=\int_0^{12x60x60} ((1.2)85x10^{-3})dt 4406\rightarrow4.406kJ

    are these answers correct
    Follow Math Help Forum on Facebook and Google+

  2. #2
    Senior Member
    Joined
    Feb 2008
    Posts
    383
    Quote Originally Posted by bigwave View Post
    1. A rechargeable flashlight battery is capable of delivering 85mA for about 12h.
    How much charge can it release at that rate?

    well i think I did this right.... what ?? me was the time given as h so looks this has to be converted to s (seconds) to do this. is this always the case?

    Q=\int_0^{12x60x60} (85x10^{-3})dt = 3672\rightarrow3.672kC

    2. If its terminal voltage is 1.2V, how much energy can the battery deliver.

    so on this one I just multiplied the voltage to the current

    W=\int_0^{12x60x60} ((1.2)85x10^{-3})dt 4406\rightarrow4.406kJ

    are these answers correct
    your answers are right.

    there is no need to use integration.

    I= Q/t
    V=W/Q

    use the above equations can give you the answers
    .
    Follow Math Help Forum on Facebook and Google+

Similar Math Help Forum Discussions

  1. [SOLVED] Generalised energy and energy (lagrangian mechanics)?
    Posted in the Advanced Applied Math Forum
    Replies: 2
    Last Post: January 16th 2012, 04:03 AM
  2. size of a charge
    Posted in the Math Topics Forum
    Replies: 4
    Last Post: January 26th 2011, 11:25 AM
  3. find charge, power, energy
    Posted in the Math Topics Forum
    Replies: 11
    Last Post: December 30th 2010, 02:15 PM
  4. kinetic energy during energy levels
    Posted in the Math Topics Forum
    Replies: 0
    Last Post: December 27th 2010, 02:12 AM
  5. Replies: 7
    Last Post: April 17th 2006, 02:04 PM

Search Tags


/mathhelpforum @mathhelpforum