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How do you find the resistance of a coil

  1. Oct 12, 2005 #1
    A coil is to be used as an immersion heater for boiling water. The coil is to operate at a voltage of V and is to heat an amount of water with a volume of v by T degrees C in a time interval of t seconds.
    Use 4190 for the specific heat capacity of water and 1000 for the density of water. How do you find the resistance of a coil that is temperature independent? (Given voltage, volume, and time)
    Last edited: Oct 12, 2005
  2. jcsd
  3. Oct 12, 2005 #2

    Tom Mattson

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    We'll help, but only after you show how you attempted the problem. That is stated in those guidelines that you agreed to, but evidently did not read.
  4. Oct 12, 2005 #3
    R=V/I, but I is not given, so does "I" have something to do with time?
  5. Oct 13, 2005 #4


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    Think in energy terms. Where it comes from and where it is going.
  6. Oct 13, 2005 #5
    The voltage=Energy/Length
  7. Oct 13, 2005 #6
    How else the energy relate?
  8. Oct 29, 2005 #7


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    Sorry, I missed your responses. If you are still interested: The electric work done by the current flowing through the coil is converted by it to heat, that is what a resistor or coil does, it converts electric energy to heat - very useful for making coffee or having a bath. This heat energy is then transferred to the water, which heats the water up. The potential difference over an electric component tells us how much electric work is done in the component for each coulomb of electric charge that flows through it.
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