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Homework Help: Transformers Help

  1. Apr 3, 2005 #1
    1) A transformer is designed to change 120 V into 10,000 V, and there are 5,000 turns in the primary. How many turns are in the secondary, assuming 100 perfect efficiency?

    2) A transformer has 420 turns in the primary and 120 in the secondary. What kind of transformer is this and, assuming 100 percent efficiency, by what factor does it change the voltage? By what factor does it change the current?
  2. jcsd
  3. Apr 4, 2005 #2
    1) The product of the potential and number of turns should be the same coming in as going out of the transformer.

    2) I'm not sure what 420 has to do with anything, but household outlets in the US are 120V (it's different in Europe, careful!). Consider also that voltage is directly proportional to current by ohm's first law V = IR.
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