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Eric
Lv 6
Eric asked in Science & MathematicsPhysics · 1 decade ago

What is the magnitude of the magnetic field?

A long solenoid with 70.0 turns/cm and a radius of 5.00 cm carries a current of 16.0 mA. A current of 2.00 A exists in a straight conductor located along the central axis of the solenoid.

(a) At what radial distance from the axis will the direction of the resulting magnetic field be at 45.0° to the axial direction?

d=I2/(2pi * n * I1) = 2.00A / (2 * pi * 70turns/cm * 0.0160A) = 0.2842m

Now they want to know what is the magnitude of the magnetic field there.

I thought I had some ideas on how to calculate this question, but none of my calculations are correct. Any help would be much appreciated. Thanks for your time!

1 Answer

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  • 1 decade ago
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    I think you use a different equation when you figure for a long solenoid. Your solenoid only specifies 70 turns per cm but doesn't give a length. Plus it says it is a long solenoid which is the clue you use the equation: B = unl,

    B = magnetic field

    u = permeability

    n = turn density

    l = current

    When I plug in the numbers (using core permeability of 200)

    B = 3.518 Tesla or 35185.8 gauss

    Look at this interactive link on solenoids called "Solenoid Magnetic Field Calculation", scroll down to third box down:

    http://hyperphysics.phy-astr.gsu.edu/hbase/magneti...

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