Magnetism and matter practice · Medium

The null points are on the axial line of a bar
magnet, when it is placed such that its south
pole points:

A steel wire of length 1 has a magnetic moment $m$. It is bent into a semicircular arc. What is the new magnetic moment?

Which of the following materials is paramagnetic at $300 {~K}$ ?

Choose the correct option

Assertion (A): Magnetic poles are only mathematical assumptions having no real existence.

Reason (R): A charged particle is moved along a magnetic field line. The magnetic force on the particle is perpendicular to its velocity.

Assertion: Ferromagnetic substance exhibits spontaneous magnetisation.
Reason: In the absence of external magnetic field, atomic dipoles of each domain are aligned in particular direction.

A magnet performs 10 oscillations per minute in a horizontal plane at a place where the angle o dip is $45^\circ$ and the total intensity is 0.707 units. The number of oscillations per minute at a place where dip angle is $60^\circ$ and total intensity is 0.5 CGS units will be

A magnet performs 10 oscillations per minute in a horizontal plane at a place where the angle of dip is 45$^ \circ$ and the total intensity is 0.707 CGS units. The number of oscillations per minute at a place where dip angle is 60$^ \circ$ and total intensity is 0.5 CGS units will be

The true value of angle of dip at a place is $60^\circ$, the apparent dip in a plane inclined at an angle of $30^\circ$ with magnetic meridian is

A rod of ferromagnetic material with dimensions $10\mathrm{\;cm} \times 0.5\mathrm{\;cm} \times 0.2\mathrm{\;cm}$ is placed in a magnetic field of strength $0.5 \times {10^4}\mathrm{A} - {\mathrm{m}^{ - 1}}$ as a result of which of which a magnetic moment of 0.5 $\mathrm{A} - {\mathrm{m}^{ - 2}}$ is produced in rod. The value of magnetic induction will be

A sphere of gold when brought towards a
powerful magnet experiences

The materials suitable for making electromagnets should have

A thin light weight rod of diamagnetic substance such as silver is suspended in uniform external magnetic field. It will align itself with its length

The coil in a tangent galvanometer is 16 cm in radius. If a current of 20 mA is to produce a deflection of $45^\circ$ then the number of turns wound on it, is (Take horizontal component of earth’s magnetic field$= 0.36 \times {10^{ - 4}}\mathrm{\;T\;and\;}{\mathrm{\mu }_0} = 4\pi \times {10^{ - 7}}\;\mathrm{Wb\;}{\mathrm{A}^{ - 1}}\mathrm{\;}{\mathrm{m}^{ - 1}}$

A bar magnet of magnetic moment $2.5\,\mathrm{Am}^2$ is free to rotate about a vertical axis through its centre. The magnet is released from rest from the east-west direction. Find the kinetic energy of the magnet as it aligns itself in the north-south direction. The horizontal component of earth's magnetic field is $0.3\,\mathrm{G}$.

The strength of earth's magnetic field on the earth's surface is of the order

At a certain place, the angle of dip is 30$^ \circ$ and the horizontal component of earth’s magnetic field is 0.50 oersted. The earth’s total magnetic filed (in oersted) is

A magnet is suspended in the magnetic meridian with an untwisted wire. The upper end of wire is rotated through $181^{\circ}$ to deflect magnet by $37^{\circ}$ from magnetic meridian. Now this magnet is replaced by another magnet and upper end of wire has to be rotated by $273^{\circ}$ to deflect magnet by $53^{\circ}$ from magnetic meridian. The ratio of magnetic moment of the two magnets respectively is

For a paramagnetic material, the dependence of the magnetic susceptibility $X$ on the absolute temperature is given as

For a diamagnetic material:

The susceptibility and permeability of a perfectly diamagnetic substance is

For which among the following house
appliances, magnet is an essential part?

A short magnet produces a deflection of $37^{\circ}$ in a deflection magnetometer in Tan- $A$ position when placed at a separation of $10 \mathrm{~cm}$ from the needle. Find the ratio of the magnetic moment of the magnet to the earth's horizontal magnetic field (in $\mathrm{~A-m}^2 \mathrm{~T}^{-1}$).

Permanent magnets are those substances that ________.

If the magnetizing field on a ferromagnetic material is increased, its permeability

Two short bar magnets of moments ' $M$ ' and $\sqrt{3} M^{\prime}$ are joined like a cross (+) This cross suspended from its centre with its plane horizontal in the earth's magnetic field. When the cross comes to equilibrium, angle made by the weaker magnet with the earth's magnetic field $B_H$ is

A magnet is parallel to a uniform magnetic field. If it is rotated by $60^\circ$, the work done is $0.8\;J$. How much work is done in moving it $30^\circ$ further

The intensity of magnetic field due to an isolated pole of strength $m$ at a point distance $r$ from it will be

Which of the following is responsible for the earth's magnetic field?

Curie law $\chi T=$ constant, relating magnetic susceptibility $(\chi)$ and absolute temperature (T) of magnetic substances, is obeyed by