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So essentially a resistor eats up/throws away energy?

  1. Jun 10, 2008 #1
    I understand that a resistor can lower current flow at the expense of heat.
    So essentially a resistor eats up/throws away energy?
    Isn't there a better way to change current flow without throwing away energy?
  2. jcsd
  3. Jun 10, 2008 #2


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    Use a voltage source of lower voltage?
  4. Jun 10, 2008 #3


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    Yep, resistors turn energy into heat.

    Sometimes the desired result is heat, say a toaster or room heater, so saying that energy is thrown away is incorrect.

    In other cases a resistor can reduce the total energy consumed, so you have to look at the big picture.

    In some cases alternate methods are used, for example switching power supplies.
  5. Jun 10, 2008 #4
    You can also use transistors to affect current flow. You'll still have power dissipated, though.
  6. Jun 10, 2008 #5


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    It is also possible that a resistor (or several of them) will supply a load to a power supply such that that power supply can supply a regulated drain instead of appearing like a high drain or a dead short.
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