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Homework Help: Open switches, current

  1. Jan 6, 2012 #1
    1. The problem statement, all variables and given/known data
    There is a circuit with 7 LEDS connected in parallel, each with a switch on its parallel. There is a battery supplied.

    The LEDS correspond to those of a digital clock for example the number 8 would light up all 7 LEDS, whilst the number 0 would light up 6 LEDS.

    Which number from 0 to 9 draws the least current from the battery (For example to light up 3 I would have to close 5 switches)

    2. Relevant equations


    3. The attempt at a solution

    I'm slightly confused. Since the voltage is remaining the same, the only thing that would make the resistance decrease would be the resistance. I think (please correct me if I am wrong) that an open switch causes infinite resistance, therefore the number with the most open switches would cause the least current, number 1 as 5 LEDS are off

    Any idea would be helpful, thanks
  2. jcsd
  3. Jan 6, 2012 #2


    User Avatar

    Staff: Mentor

    I agree that displaying 1 draws the least current.
  4. Jan 6, 2012 #3
    Thank you very much, question is answered, this thread is now obsolete.
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