Define the function of the small cylinder in the construction of a galvanometer.

(N/A) In a moving coil galvanometer,a soft iron cylinder is placed inside the coil. The primary functions of this cylinder are:
$1$. It increases the strength of the magnetic field by concentrating the magnetic flux lines through the coil due to its high permeability.
$2$. It makes the magnetic field radial,ensuring that the plane of the coil is always parallel to the magnetic field lines,regardless of the coil's orientation. This results in a linear relationship between the current and the deflection,i.e.,$\tau = NIAB \sin(90^{\circ}) = NIAB$.