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Permanent Magnets:

Permanent magnets are made of hard materials i.e., materials which have a broad hysteresis loop so that they are not subject to self-demagnetization. In order that the volume of the permanent magnet is small, the product of the material used should be large.

Pointers and scales:

Instrument scales and pointers may be considered together in two classes;

(i) those intended for reading quickly (in case of swichboard instruments at a distance) and (ii) those intended for close accurate reading.

However , in all cases, the weight and inertia of pointer must be reduced so as to reduce the load on the bearing and to avoid necessity of excessive damping torque.

The pointer motion is limited by buffers or stops to a little more than the scale. These stops are constructed as very light springs so that the pointer is not bent when it strikes them sharply on a sudden overload or reversal of the operating current.