7. 2 Neutral Points

1.1 Properties of Magnet

3.1 Magnetic Dipole Moment
3.2 Magnetic Field Due to a Magnetic Dipole
3.3 Torque Acting on a Magnetic Dipole
3.4 Potential Energy of a Magnetic Dipole in a Uniform Magnetic Field

7.1 Some important terms
7. 2 Neutral Points

9.1 Tangent Galvanometer

Neutral point of a bar magnet is a point at which the resultant magnetic field of a bar magnet and horizontal component of earth’s magnetic field are zero. When north pole of a bar magnet is placed towards south pole of the earth. then neutral point is obtained on axial line. $$B = \frac{{{\mu _o}}}{{\frac{{4\pi {\text{ }}2Mr}}{{{{({r^2}--{l^2})}^2}}}}} = {\text{ }}H$$ If $$r>>1,$$ then, $$B = \frac{{{\mu _o}}}{{\frac{{4\pi {\text{ }}2M}}{{{r^3}}}}} = H$$ When north pole of a bar magnet is placed towards north pole of the earth, then neutral point is obtained on equatorial line $$B = \frac{{{\mu _o}}}{{\frac{{4\pi 2Mr}}{{{{({r^2}--{l^2})}^2}}}}} = H$$ If $$r > > 1,$$ then $$B = \frac{{{\mu _o}}}{{\frac{{4\pi {\text{ }}2M}}{{{r^3}}}}} = H$$