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Original magnet MOS is bent at O , the mid point at 60 °. All sides are equal� The mutual interaction force between two small magnets of moments
M 1 and M 2 is given by�
F = K 6M 1 M 2 / d 4 in end- on position . Here , d denotes the separation between magnets .
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� Magnetic length = 5 / 6 * geometric length of magnet . �
� Cause of diamagnetism is orbital motion and cause of Para magnetism is spin motion of electrons . Cause of ferromagnetism lies in formation of domains . �
� The perpendicular bisector of magnetic axis is known as neutral axis of magnet . Magnetism at neutral axis is zero and at poles is maximum . �
� For steel coercivity is large . However , retentivity is comparatively smaller in case of steel . So , steel is used to make permanent magnets . �
� For soft iron , coercivity is very small and area of hysteresis loop is small . So , soft iron is an ideal material for making electromagnets . �