Consider a bar magnet of length l and magnetic moment m at a distance r fróm its mid point, where `r >>l` Show that the magnetic field B due, to this bar is
`vecB = (mu_ovecm)/(4pir^3)mu_o` alog equator.

(Attempt any nine of the following questions)A current carrying solenoid is shown be low. Show that the magnetic field intensity at point P be B= mu_0/(4pi) (2m)/r^3 Where the symbols have their usual meaning.

Two parallel Co-axial Coils of equal radius R and- numbers of turn N carrying equal currents I in same direction.are separated by a distance | R. Show that the magnetic field intensity B on the axis around the mid point between the coils is uniform over a very small distance as compared to R and is given by- B = (4/5)^(3/2) (mu_0IN)/R