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Homework Help: Real Wattage

  1. Aug 19, 2005 #1
    If you have a globe marked 70W and 240V and you connect it to one end of cord( which has two wires, each of 0.6 ohms), and the other end of the cord is connected to a 240V outlet, what is actual power dissipated by the globe?
  2. jcsd
  3. Aug 19, 2005 #2

    Chi Meson

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    Here are a few pushes in the right direction.

    The rating on the bulb (70W at 240 V) does not mean that either wattage or voltage is a "set" constant for the bulb. But from these two values, you can find a property that is constant for the bulb, specifically its resistance (assuming there is not significant difference in temperature between the rated and actual power output).

    So, assume a voltge of 240V across the circuit, find the total current through the circuit (using total resistance), then find power output of the bulb.
  4. Aug 20, 2005 #3
    Thanx for that advice, it was very helpful
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