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How to determine heat from resistance?

  1. Sep 22, 2011 #1
    Is there a formula of some sorts that can determine the thermal energy released from electricity flowing through a wire, knowing the wire's resistance?
     
  2. jcsd
  3. Sep 23, 2011 #2
    Yes , there is formula. You can even derive it logically. You can do it! Work done=Energy manifested is a basic logical equation in fundamental physics.

    Thermal energy released from wire due to its heating = I2RT
    Thermal energy is not released from electricity. It is released due to resistance in a wire because work is done on per unit charge to move it through certain displacement in a wire. On moving a unit charge it faces obstruction or friction of wire. This work done is manifested in form of heat energy in a wire.

    You know ,
    V=W/Q
    W=VQ
    So Heat energy released or work done by wire :
    Thermal energy released from wire due to its heating = VQ
    Thermal energy released from wire due to its heating = IR x IT
    Thermal energy released from wire due to its heating = I2RT

    Where I is current flowing in wire , R is resistance and T is time.

    R=k l/a
    a is area of cross section in a wire and l is length of wire.
    k is (rho) or resistivity in a wire.

    Thermal energy released from wire due to its heating = k I2 T l/a
     
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