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Q & A: AC to DC and appliance current drain

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Most recent answer: 04/27/2008
Q:
How is AC current changed into DC current and why are our appliances (dishwasher, microwave, etc.) still using electricity if they are turned off?
- Tara Paranjpe (age 14)
Champaign, Illinois, United States
A:
Hi Tara,
AC (alternating current) can be changed into DC (direct current) by means of an electronic device called a rectifier.  The main component of a rectifier is called a diode which allows current to pass one way but not the other.  Several of these diodes plus some other smoothing  filters can produce a DC voltage.   See http://en.wikipedia.org/wiki/Rectifier for more details.             As to your second question:   some devices draw a little stand-by current to run small electronic accessories.  For example the microwave oven in my house has an electronic clock that keeps runing even when the microwave part of the oven is not heating.  This takes a negligible amount of power.  My dishwasher doesn't have a clock so I think it is really off when not in use.

LeeH

(published on 04/27/2008)

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