Distribution of magnetic field strength H along the axis of round “thin” solenoids with different aspect ratios of length L to diameter d, all values are plotted as relative to the “ideal” $H=N·I/L$.
For a “long” solenoid (such that L»d) the field is very uniform in the middle half of the length (from x=-0.25 to x=0.25). At the edges of the field reduces roughly to half of the value in the middle.
The data is generated by S. Zurek, using equations from: Fausto Fiorillo, Measurement and Characterization of Magnetic Materials, Academic Press, 2005, ISBN 9780122572517
solenoids_round_thin_magnetica.png
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