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Quick question about the flux density through a solenoid.

  1. Apr 4, 2008 #1


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

    the flux density through a solenoid is given by

    [tex]B=\mu_o n I[/tex]

    Where n is the number of turns per unit length.

    The number of field lines per unit area is proportional to B.

    I am assuming that at or near the centre of the solenoid the number of field lines per unit area decreases so B decreases.
    If that is true, then how come the formula stated above doesn't account for distance from the centre of the solenoid?
  2. jcsd
  3. Apr 4, 2008 #2
    That's not the flux through a solenoid, that's the magnetic field strength. The magnetic field is uniform inside the solenoid (like how a parallel-plate capacitor has a uniform electric field between the two plates).
  4. Apr 4, 2008 #3


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    Magnet flux density is the same as field strength?

    The reason I ask is that there is a question in which a Hall probe measures tehe magnetic flux density in a solenoid. They take measurements fromt the centre of the solenoid(x=0cm) until the end of the solenoid(x=16cm).
    The results showed that as the x increases, B decreased.
    Then the question asked "What conclusions can be made about the (i) the region where the formula ([itex]B=\mu_0 n I[/itex] applies"
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