Magnetism and Matter — Class 12 Physics PYQs

A diamagnetic substance is brought, one by one, near the north pole and the south pole of a bar magnet. It is
(A) repelled by north pole and attracted by south pole.
(B) attracted by north pole and repelled by south pole.
(C) attracted by north pole as well as by south pole.
(D) repelled by north pole as well as by south pole.

A soft iron rod X is allowed to fall on the two poles of a U shaped permanent magnet as shown in figure. A coil is wrapped over one arm of the U shaped magnet.
During fall of the rod, the current in the coil will be
(A) clockwise current
(B) anticlockwise current
(C) alternating current
(D) zero

A bar magnet of magnetic moment 2.5 JT${}^{-1}$ lies aligned with the direction of a uniform magnetic field of 0.32 T.
(a) Find the amount of work done to turn the magnet so as to align its magnetic moment (i) normal to the field direction, and (ii) opposite to the field direction.
(b) What is the torque on the magnet in above cases (i) and (ii) ?

Above Curie temperature, a
(A) ferromagnetic material becomes diamagnetic.
(B) ferromagnetic material becomes paramagnetic.
(C) paramagnetic material becomes ferromagnetic.
(D) paramagnetic material becomes diamagnetic.

The material which is not suitable for making a permanent magnet is
(A) Steel
(B) Ticonal
(C) Lead
(D) Alnico

The magnetic field and angle of dip at a place on the earth are 0.3 G and 30°, respectively. The value of vertical component of the earth's magnetic field at the place is ___________ .

The magnetic field lines are _________ by a paramagnetic substance.

The magnetic field lines are ___________ by a diamagnetic substance.

State Gauss's law for magnetism. Explain its significance.
(b) Write the four important properties of the magnetic field lines due to a bar magnet.
OR
Write three points of differences between para-, dia- and ferro- magnetic materials, giving one example for each.

A bar magnet of magnetic moment 6 J/T is aligned at 60° with a uniform external magnetic field of 0.44 T. Calculate (a) the work done in turning the magnet to align its magnetic moment (i) normal to the magnetic field, (ii) opposite to the magnetic field, and (b) the torque on the magnet in the final orientation in case (ii).