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Homework Help: Power, Voltage and Current - Hairdryer Problem

  1. Feb 16, 2010 #1
    1. The problem statement, all variables and given/known data
    A typical household circuit is capable of carrying 30.0 A of current at 120 V before the circuit breaker will trip. How many 1500-W hair dryers can run off one such circuit?

    Use the relation between power, current and voltage. Also, remember hair dryers come in integer units.

    2. Relevant equations
    P = VI

    3. The attempt at a solution
    P = 120 * 30 = 3600
    3600/1500 = 2.4

    This is incorrect and I don't understand why. Am I missing something?
  2. jcsd
  3. Feb 16, 2010 #2


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    What's 0.4 of a hairdryer?
  4. Feb 16, 2010 #3
    Ah, thank you. I only put 2.4 because they said "Also, remember hair dryers come in integer units" so I thought they wanted the .4.

    Thank you!
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