Magnetism and matter practice · Medium

The magnetism of a magnet is due to

The intensity of magnetic field is $H$ and moment of magnet is $M$. The maximum potential energy is

The absolute magnetic permeability is measured to be $0.12 \mathrm{~T} \mathrm{~A}^{-1} \mathrm{~m}$. Find its relative permeability and susceptibility.

When a piece of a ferromagnetic substance is put in a uniform magnetic field, the flux density inside it is four times the flux density away from the piece. The magnetic permeability of the material(in $\mathrm{N}/{\mathrm{A}^2}$) is

Assertion: $MnO_2$ is ferromagnetic.
Reason: Domains are equally aligned in parallel and anti parallel direction.

In a vibration magnetometer, the time period of a bar magnet oscillating in horizontal component of earth’s magnetic field is 2 s. When a magnet is brought near and parallel to it, the time period reduces to 1 s. The ratio $\frac{F}{H}$ of the fields, $F$ due to magnet and $H$, the horizontal component will be

The magnetic induction in air at a distance $d$ from an isolated point pole of strength $m$ unit will be

A coil made of copper suspended from a fixed support is oscillating freely. If a magnetic dipole is brought near the coil, the coil will

The magnetic dip angle at magnetic equator of the earth is

In a ferroelectric material, as the applied field is gradually reduced to zero, the polarization still left is known as

A deflection magnetometer is adjusted in the usual way. When a magnet is introduced, the deflection observed is $\mathrm{\theta }$, and the period of oscillation of the needle in the magnetometer is $T$. When the magnet is removed, the period of oscillation is ${T_0}$.Find the relation between $T\;\mathrm{and}\;{T_0}$ is

At a place, true dip angle is $60^{\circ}$. The apparent dip when plane of the dip circle is at an angle $60^{\circ}$ with the magnetic meridian is

Which of the following is true

The correct definition of Meissner effect is

The incorrect statement regarding the lines of force of the magnetic field $B$ is

There are four light-weight-rod samples, $A,\;B,\;C,D$ separately suspended by threads. A bar magnet is slowly brought near each sample and the following observations are noted
(i) $A$ is feebly repelled
(ii) $B$ is feebly attracted
(iii) $C$ is strongly attracted
(iv) $D$ remains unaffected
Which one of the following is true

The magnetic field due to a small magnetic dipole of magnetic moment $M$, at distance $r$ from the centre on the equatorial line is given by (in M.K.S system)

A magnetic needle vibrates in a vertical plane parallel to the magnetic meridian about the horizontal axis. Its frequency is $n$. If the plane of oscillation is turned about a vertical axis by $90^{\circ}$, the frequency of oscillation will be.

Assertion (A): A disc-shaped magnet is levitated above a super conducting material that has been cooled by liquid nitrogen.

Reason (R): Super conductors repel a magnet.

Work done in rotating a bar magnet from 0 to angle $\theta$ is :

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

Assertion (A): The true geographic north direction is found by using a compass needle.

Reason (R): The magnetic meridian of the earth is along the axis of rotation of the earth.

Assertion (A) Above Curie temperature, a ferromagnetic material becomes paramagnetic.

Reason (R) When a magnetic material is heated to very high temperature, it loses its magnetic properties.

A magnetic needle is kept in a uniform magnetic field of induction $0.5 \times \,{10^{ - 4}}$ telsa. Its makes oscillations per minute. If it is kept in a field of induction $2 \times \,{10^{ - 4}}$ telsa. Then its frequency is

Susceptibility of ferromagnetic substance is

A long copper tube of inner radius ${R}$ carries a current $i$. The magnetic field $B$ inside the tube is

The material used for permanent magnet has :

Magnetic lines of force due to a bar magnet do
not intersect because

Assertion (A): Time period of vibrations of a pair of magnets in sum position is always smaller than in difference position.

Reason (R): $\mathrm{T}=2 \pi \sqrt{I / M B_H}$, where symbols have their standard meaning.

A watch glass containing some powdered substance is placed between the pole pieces of a magnet. Deep concavity is observed at the centre. The substance in the watch glass is