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help resolving equation

  • 14-10-2012 11:57am
    #1
    gan23
    Registered Users, Registered Users 2 Posts: 80 ✭✭


    Hi,
    I am doing a part time degree and have come up against this equation. I can fill in the different variables but i dont know what to do with it after a certain point.

    Vc = Vs(1-e-t/rc),

    Vc = 5.96(1-e-20/12.2)

    the part afte e (-20/12.2) should be superscript i.e. to the power of. Does this make sense??
    Any help on how to complete this?
    Thanks


Comments

  • #2
    2rkehij30qtza5
    Closed Accounts Posts: 1,476 ✭✭✭2rkehij30qtza5


    gan23 wrote: »
    Hi,
    I am doing a part time degree and have come up against this equation. I can fill in the different variables but i dont know what to do with it after a certain point.

    Vc = Vs(1-e-t/rc),

    Vc = 5.96(1-e-20/12.2)

    the part afte e (-20/12.2) should be superscript i.e. to the power of. Does this make sense??
    Any help on how to complete this?
    Thanks

    Well you can't complete it if two variables are unknown! So is e Euler's number? Which would be 2.718....not sure if this is the case here. In what context is the equation??


  • #3
    gan23
    Registered Users, Registered Users 2 Posts: 80 ✭✭gan23


    The equation is to calculate the voltage of a capacitor at a particular time during its charging phase. I dont remember anything about Eulers number? Is it something to do with 1(-exponential) ?
    to be honest this is my problem, Im not exactly sure what the 1-e part actually means. this was part of a lab we did. but we havent done the lecture for it yet!
    Sorry if this isnt making much sense...


  • #4
    2rkehij30qtza5
    Closed Accounts Posts: 1,476 ✭✭✭2rkehij30qtza5


    Hmmm I think it would be Euler's constant. It's quite a long number from what I can remember..google it to get it. I don't have time to do the equation out here (two toddlers swinging off me!) but yes you would use Euler's number in this context.
    Someone else might correct me if I am wrong.


  • #5
    gan23
    Registered Users, Registered Users 2 Posts: 80 ✭✭gan23


    Ok thanks Galwaygirl. Ill check it out


  • #6
    2rkehij30qtza5
    Closed Accounts Posts: 1,476 ✭✭✭2rkehij30qtza5


    gan23 wrote: »
    Ok thanks Galwaygirl. Ill check it out

    Yep work it out and see if the answer makes sense.


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  • #7
    gan23
    Registered Users, Registered Users 2 Posts: 80 ✭✭gan23


    Great, it seems to be working out!
    comparing calculated voltage with measured, its close at a each point I've checked.

    Thanks a lot :-)


  • #8
    2rkehij30qtza5
    Closed Accounts Posts: 1,476 ✭✭✭2rkehij30qtza5


    gan23 wrote: »
    Great, it seems to be working out!
    comparing calculated voltage with measured, its close at a each point I've checked.

    Thanks a lot :-)

    Great glad it worked out :)


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