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Homework Help: Determine the base unit for the magnetic flux

  1. Feb 22, 2009 #1
    1. The problem statement, all variables and given/known data
    The e.m.f E of a battery is given by [tex]E = \frac{P}{I}[/tex] where P is the power supplied from the battery when current I flows through it. An e.m.f. [tex]{E_c}[/tex] can also be induced in a coil when the magnetic flux, [tex]\Phi [/tex], associated with it changes with time, t, as expressed by [tex]{E_c} = \frac{{d\Phi }}{{dx}}[/tex]. Determine the base unit for the magnetic flux.

    Answer is [tex]kg{m^2}{A^{ - 1}}{s^{ - 2}}[/tex]

    2. Relevant equations
    [tex]E = \frac{P}{I} = \frac{{kg{m^2}{s^{ - 2}}}}{{A \cdot s}}[/tex]


    3. The attempt at a solution
    I tried to integrate [tex]E = \frac{P}{I} = \frac{{kg{m^2}{s^{ - 2}}}}{{A \cdot s}}[/tex] but was stuck at getting the answer. Please help
    Thanks!
     
  2. jcsd
  3. Feb 22, 2009 #2
    There is no need to integrate,just rearrange your equation to make phi the subject then insert the base units and tidy it up.
     
  4. Feb 22, 2009 #3

    rl.bhat

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    Homework Helper

    Power = workXtime= kg*m^2*s^-3
    flux = Pxs/I.
    Now find the final unit.
     
  5. Feb 22, 2009 #4
    Flux=Px/I.You have the right units for P,x is s and I is A
     
  6. Feb 22, 2009 #5
    Thanks for the replies, however, aren't we suppose to extract information that is provided by the question?

    How do you guys deduce the answer from [tex]{E_c} = \frac{{d\Phi }}{{dx}}[/tex] ?
     
  7. Feb 22, 2009 #6
    Phi=Ex
     
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