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Homework Help: Power absorbed by heater

  1. Nov 23, 2009 #1
    1. The problem statement, all variables and given/known data
    A heater rated at 2000 W operating at 250 V is used on a supply of 230 V. If the resistance of the heater is independent of temperature, calculate the power absorbed by the heater.

    2. Relevant equations

    3. The attempt at a solution
    resistance of heater :

    [tex]R=\frac{V^2}{P}=31.25~ \Omega[/tex]

    The power absorbed :

    [tex]P'=\frac{230^2}{31.25}=1692.8 ~W[/tex]

    Do I get it right?

  2. jcsd
  3. Nov 23, 2009 #2


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    Science Advisor
    Homework Helper

    You don't need to actually work out the resistance, you know power is the ratio of the voltage^2
    = 2000*(230^2/250^2)

    ps. careful about how many significant figures
  4. Nov 23, 2009 #3
    Hi mgb_phys

    Ok, thanks a lot !! :smile:
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