Why the poles of permanent magnet are "concave cylindrical" in case of a galvanometer?
Dear student,
When the loop gets deflected its plane has to be always in the direction of magnetic field. So the magnetic field vector and area vector of the loop is always perpendicular. So torque will remain the same as n B i A sin 90 = n B i A
n = number of turns, B magnetic field induction, i current and A area of cross section of the loop
So the best way to achieve this is to have a RADIAL magnetic field which is possible when we have a concave shaped magnet.
Regards
When the loop gets deflected its plane has to be always in the direction of magnetic field. So the magnetic field vector and area vector of the loop is always perpendicular. So torque will remain the same as n B i A sin 90 = n B i A
n = number of turns, B magnetic field induction, i current and A area of cross section of the loop
So the best way to achieve this is to have a RADIAL magnetic field which is possible when we have a concave shaped magnet.
Regards