# Encyclopedia Magnetica™

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calculator:magnet_cylindrical

#### Calculator of H along axis of cylindrical magnet This section is an interactive calculator.
Magnetic field strength H of a cylindrical permanent magnet along its axis
(based on magnet diameter D) $H(x) = \frac{B_r}{2·µ_0}· \left( \frac{x+L}{\sqrt{D^2 /4 +(x+L)^2}} - \frac{x}{\sqrt{D^2 /4 +x^2}} \right)$ (A/m)
(based on magnet radius R) $H(x) = \frac{B_r}{2·µ_0}· \left( \frac{x+L}{\sqrt{R^2+(x+L)^2}} - \frac{x}{\sqrt{R^2+x^2}} \right)$
where: $B_r$ - remanence (flux density) of the permanent magnet (T), $L$ - axial length (m) of the cylindrical magnet, $D$ - diameter (m) of the of the magnet, $R$ - radius (m) of the of the magnet, $x$ - location (m) from the surface of the magnet (surface is synonymous with x = 0), μ0 - magnetic permeability of vacuum (H/m)

Remanence Br = (T)

Diameter D =

Length L =

Position on axis x =

H =      B0) =

Notes: This equation is valid only for a uniformly magnetised cylindrical magnet, for the field along its axis.1) The value of B(μ0) is for vacuum. 