A moving coil galvanometer works on the principle that when a current carrying loop or coil is placed in the uniform magnetic field, it experience a torque.
(i) Radial magnetic field, produced by clindrical poles of permanent magnet of galvanometer is always parallel to the plane of the coil. Torque produced in the coil of galvanometer is given by,
`tau = NIABsin theta`
(ii) Cylindrical soft iron core, when placed inside the core makes teh magnetic field stronger and radical between it and pole pieces. Irrespective of position of rotation of coil, magnetic field is always parallel to the plane.
Current sensitivity `= (phi)/(I)= (phi(NAB))/(Kphi) = (NAB)/(K)`
No , Galvanometer cannot be used for measuring current as it is very sensitive instrument, even for small value of current it gives full scale deflection.
Galvanometer can be used in series connection for measuring current, it ha large resistance so, the value of current will not be accurately measured.
