Power and Voltage Help (I blanked)!

Discussion in 'General Science' started by NinaFarac, Jan 1, 2016.

  1. NinaFarac

    Thread Starter New Member

    Jan 1, 2016
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    0
    Hey everyone, I'm having a 'blanking' moment:
    Today, my teacher gave us an example of an electrical source that had enough power to power a LED light, but not enough voltage. We then had to offer a suggestion to change the circuit in order to make enough voltage.
    Can someone please explain how you can have enough power, but not enough voltage? I don't see how this fits in the general power-voltage relationship.

    Thank you in advance!
     
  2. djsfantasi

    AAC Fanatic!

    Apr 11, 2010
    2,810
    834
    Power is what? In other words, power is the relationship between what two values!

    The answer is P=VxI. If the voltage is too low, and the current available is higher than necessary - you have sufficient power but not enough voltage.

    Take a typical but mythical LED circuit for illustration. The LED specs say it has a forward voltage of 2V and typical current of 15ma. It's power requirement would be 0.03W

    Now consider a power supply of 1V and 30ma. Power is also 0.03W. But there is insufficient voltage to illuminate the LED; it requires 2V.
     
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  3. NinaFarac

    Thread Starter New Member

    Jan 1, 2016
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    0
    Thank you for your reply djsfantasi! I was able to work it out after I posted the thread :p
     
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