Magnets that retain magnetism for a very long period of time

Temporary magnets retain magnetism only for a short period of time.

Assertion: Substances which at room temperature retain their ferromagnetic property for a long period of time are called permanent magnets. Reason: permanent magnet can be made by placing a ferramagnetic rod in a solenoid and passing current through it.

Magnetic keepers help to retain magnetism.

Which of the following retains magnetism for a long time?

Permanent magnets retain magnetism only for a short time.

The perio of oscillation of a magnet in vibration magnetometer is 2 sec. The period of oscillation of a magnet whosr magnetic moment is four times that of the first magnet is

Two bar magnets having same geometry with magnetic moments M and 2M, are firstly placed in such a way what their similar poles are same side then its time period of oscillation is T_1 . Now the polarity of one of the magnet is reversed then time period of oscillation will be:-

A bar magnet is released from rest along the axis of a very long, vertical copper tube. After some time the magnet.

The magnetism acquired by a magnetic material as long as it is in contact with a magnet

A bar magnet oscillates in a region of uniform magnetic field with time period T . Now , a piece of wood identical in all respects in terms of mass and length is joined with bar magnet as shown . The new time period of oscillation is