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Power transfer and impedence matching.

  1. Mar 30, 2009 #1
    What is the physical explanation for the power transfer in a circuit being maximum when the resistance of the system is equal to the internal resistance?

    maybe heat loss?

    any help would be appreciated as i understand the mathematical proof but do not know much about the physical causes.
     
  2. jcsd
  3. Mar 30, 2009 #2

    Mapes

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    If the resistance of the load [itex]R_\mathrm{load}[/itex] is very low (so that the current I is approximately constant through the load and independent of [itex]R_\mathrm{load}[/itex]), then the power transfer [itex]I^2R_\mathrm{load}[/itex] will be small. If the resistance of the load is very high (so that the voltage V is approximately constant across the load and independent of [itex]R_\mathrm{load}[/itex]), then the power transfer [itex]V^2/R_\mathrm{load}[/itex] will be small. In between these two extremes is a happy medium, specifically at [itex]R_\mathrm{load}=R_\mathrm{source}[/itex].
     
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