In the principle of operation of Galvanometer, Which one is rotating either coil or core? If core and coil both are rotating then deflecting torque is directly proportional to square of current flowing through it and core loss has to be taken into account. Explain the principle of working of Galvanometer in detail with suitable diagram?
The torque on a current loop in a uniform magnetic field is used to measure
electrical magnetic field is used to measure electrical currents. This current measuring device is called a moving coil galvanometer.
The galvanometer consists of a coil of wire often rectangular, carrying the current to be measured. There are generally many turns in the coil to increase its sensitivity. The coil is placed in a magnetic field such that the lines of B remain nearly parallel to the plane of wire as it turns. This is achieved by having a soft iron cylinder placed at the center of the coil. Magnetic field lines tend to pass through the iron cylinder, producing the field configuration. The moving coil is hung from a spring which winds up as the coil rotates; this winding up produces a restoring torque proportional to the winding up (or twisting) of the spring, i.e. to the angular deflection of the coil. The coil comes to equilibrium when this restoring torque k balances the torque due to the magnetic field balances the torque due to the magnetic field. Since by design field lines are radial,
we have sin theta ~ 1, so that for equilibrium
k ø = INBA
NBA
ø = ------ I
k
Thus the deflection ø of the galvanometer is proportional to the electric current I passing through it.
www.youtube.com/watch?v=_sD_5iyHl3s
Dear Anup Kumar, Can you tell which company meters are gives most accurate readings and why?
That is very difficult to answer. presently, i am using scientech company instruments. it is not accurate. Almost every instruments have low sensitivity and drift error. If i would get some ideas about some different companies then i would tell you.
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