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Homework Help: Transformer questions - primary, secondary, gaaaah

  1. Mar 13, 2010 #1
    Transformer questions - primary, secondary, gaaaah!!

    Hello, I really need help with this. Much appreciated!!! Thank you so much in advance for any help!


    1. The problem statement, all variables and given/known data

    A step-up transformer has exactly 100 turns in the primary and exactly 200 turns in the secondary. If the voltage in the primary is 100 V ± 2 %, what is the voltage in the secondary?

    a. 200 V ± 4 V
    b. 200 V ± 4 %
    c. none of the other answers
    d. 100 V ± 4 %
    e. 200 V ± 2 V

    2. Relevant equations

    Vs/Vp=Ns/Np

    3. The attempt at a solution

    OK now here, I know the voltage should be 200V. But the uncertainty .... ? I really don't know where to even begin with that. I chose answer b. 200 V ± 4 %, and it was wrong.
     
  2. jcsd
  3. Mar 13, 2010 #2
    Re: Transformer questions - primary, secondary, gaaaah!!

    Thank you!
     
  4. Mar 13, 2010 #3
    Re: Transformer questions - primary, secondary, gaaaah!!

    There is no more uncertainty introduced in the secondary voltage, so it is still +/- 2%. To trick you, they omitted this selection and instead put the real value of 2% which is just 2% of 200 (4 volts)
     
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