newbie question about circuit layout

Discussion in 'Homework Help' started by curry87, Jul 4, 2010.

  1. curry87

    Thread Starter Member

    May 30, 2010
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    0
    If circuits a and b have the same current but b led has a vf of 9v will this be damaging to the led even though the current is limited ?


    How do i limit the current at 9 v supply dc to .1amp if i only have .250watt resistors what layout can i use to dissipate the power and limit the current without buying a 1 watt resistor?
     
  2. bertus

    Administrator

    Apr 5, 2008
    15,648
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  3. beenthere

    Retired Moderator

    Apr 20, 2004
    15,815
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    Ohm's law is enough to let you determine the resistance. Use the form R = E/I, where you substitute in your voltage and the desired current. Power dissipation in the resistors comes from I^2*R.
     
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