Describe the working principle of a moving coil galvanometer. Why it is necessary to use ( i ) a radical magnetic field ( ii ) a cylindrical soft iron core in a galvanometer ? Write the expression for current sensitivity of the Galvanometer.
Answers
in the radial field a cylindrical soft iron core should be used because the soft iron core helps to move more and more magnetic field line through it and a cylindrical magnet should also be used.
Explanation:
A moving coil galvanometer works on the principle that when a current carrying loop or coil is plcaed in the uniform magnetic field, it experiences a torque.
A moving coil galvanometer works on the principle that when a current carrying loop or coil is plcaed in the uniform magnetic field, it experiences a torque.(i) A radial magnetic field, produced by cylendrical poles of permanent magnet of galvanometer is always parallel to the place of the coil. Torque produced in the coil of galvanometer is given by ,
expression is above in the figure
(ii) Cylindrical soft iron core, when placed inside the core makes the 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.
(ii) Cylindrical soft iron core, when placed inside the core makes the 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 = φ / I = φ(NAB) / Kφ = NAB / K
(ii) Cylindrical soft iron core, when placed inside the core makes the 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 = φ / I = φ(NAB) / Kφ = NAB / KNo, galvanometer cann't be used for measuring current as it is very sensitive instrument, even for small value of current it gives full scale deflection.
(ii) Cylindrical soft iron core, when placed inside the core makes the 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 = φ / I = φ(NAB) / Kφ = NAB / KNo, galvanometer cann't 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 has large resistance. So, the value of current will not be accurately measured.
