Gauss ’ s Law in Magnetism
Surface integral of magnetic field over any closed or open surface is always m .
This law tells that the net magnetic flux through any surface is always zero .
[ When in an atom any electron revolve in an orbit it is equivalent to a current loop . Therefore , atom behaves as a magnetic dipole ].
Magnetic Moment of an Atom Magnetic moment of an atom M = 1 / 2 eωr 2 where e = charge on an electron , ω = angular velocity of electron and r = radius of orbit . or M = n eh / 4πm
where h = Planck ’ s constant and m ~ mass of an electron and eh / 4πm = μ B , called Bohr magneton and its value is 9.27 * 10 -24 A-m 2 .
Earth ’ s Magnetism Earth is a huge magnet . There are three components of earth ’ s magnetism
( i ) Magnetic Declination ( θ ) The smaller angle subtended between the magnetic meridian and geographic meridian is called magnetic declination .
( ii ) Magnetic Inclination or Magnetic Dip ( δ ) The smaller angle sub tended between the magnetic axis and horizontal is called magnetic inclination on magnetic dip .