Magnetism and Matter

If the given figure shows the relation between magnetic field ( $B$-along $Y$-axis) and magnetic intensity ( $H$-along $X$-axis) of a ferromagnetic material, then the point that represents coercivity of the material is

A sample of a ferromagnetic iron in the shape of a cube of side $1.0 \mu \mathrm{~m}$ contains $8.7 \times 10^{28}$ atoms per cubic metre and the magnetic dipole moment of each iron atom is $93 \times 10^{-24} \mathrm{Am}^2$. Then, the maxi...

A sample of paramagnetic salt contains $2 \times 10^{24}$ atomic dipoles each of dipole moment $15 \times 10^{-23} \mathrm{JT}^{-1}$. The sample is placed under homogeneous magnetic field of 0.6 T and cooled to a temperature 4.2 K . The deg...

Materials suitable for permanent magnets should have

The work done in rotating a bar magnet which is initially in the direction of a uniform magnetic field through $45^{\circ}$ is $W$. The additional work to be done to rotate the magnet further through $15^{\circ}$ is

A short bar magnet has a magnetic moment of $0.48 \mathrm{JT}^{-1}$. The magnitude of magnetic field at a point at 10 cm distance from the centre of the magnet on its axis is

A short bar magnet of magnetic moment $10^4 \mathrm{JT}^{-1}$ is free to rotate in a horizontal plane. The work done in rotating the magnet slowly from the direction parallel to a horizontal magnetic field of $4 \times 10^{-5} \mathrm{~T}$ ...

A short bar magnet is placed in a uniform magnetic field of 2 T such that the axis of the magnet makes an angle of $45^{\circ}$ with the direction of the magnetic field. If the torque acting on the magnet is $0.36 \sqrt{2} \mathrm{~N}-\math...

The relation between $\mu$ and $H$ for a specimen of iron is $\mu=\left[\frac{1.4}{H}+12 \times 10^{-4}\right] \mathrm{Hm}^{-1}$. The value of $H$ which produces flux density of 1 T will be ( $\mu=$ magnetic permeability, $H=$ magnetic inte...

If the vertical component of the earth's magnetic field is 0.45 G at a location and angle of dip is $60^{\circ}$, then magnetic field of earth in that location is

At a place the horizontal component of earth's magnetic field $3 \times 10^{-5} \mathrm{~T}$ and the magnetic declination is $30^{\circ}$. A compass needle of magnetic moment $18 \mathrm{Am}^2$ pointing towards geographic north at this plac...

Any magnetic material loses its magnetic property when it is

At a place where the magnitude of the earth's magnetic field is $4 \times 10^{-5} \mathrm{~T}$, a short bar magnet is placed with its axis perpendicular to the earth's magnetic field direction. If the resultant magnetic field at a point at ...

The domain in ferromagnetic material is in the form of a cube of side $2 \mu \mathrm{~m}$. Number of atoms in that domain is $9 \times 10^{10}$ and each atom has a dipole movement of $9 \times 10^{-24} \mathrm{Am}^2$. The magnetisation of t...

A magnet suspended in a uniform magnetic field is heated, so as to reduce its magnetic moment by $19 \%$. By doing this, the time period of the magnet approximately

A solenoid has a core of a material with relative permeability 400 . The windings of the solenoid are insulated from the core and carry of 4 A . If the number of turns is 500 per metre, then the magnetising field is

One of the following substances having the tendency to move from stronger region to the weaker region of the magnetic field is

Among the following the unit of permeability is NOT represented by

Two short magnets of equal dipole moments \(M\) are fastened perpendicularly at their centres. The magnitude of the magnetic field at a distance \(d\) from the centre on the bisector of the right angle is
(\(\mu_0=\) Permeability of free sp...

A compass needle oscillates 20 times per minute at a place where the dip is \(45^{\circ}\) and the magnetic field is \(B_1\). The same needle oscillates 30 times per minute at a place where the dip is \(30^{\circ}\) and magnetic field is $$...

A magnetic needle free to rotate in a vertical plane parallel to the magnetic meridian has its north tip pointing down at \(30^{\circ}\) with the horizontal. The horizontal component of the earth's magnetic field at the place is 0.3 G . The...

A steel wire of length \(l\) and magnetic moment \(M\) is bent into a semicircular arc of radius \(R\). The new magnetic moment is

A paramagnetic sample showing a net magnetisation of \(0.8 \mathrm{~A} \mathrm{~m}^{-1}\), when placed in an external magnetic field of strength \(0.8 \mathrm{~T}\), at a temperature \(5 \mathrm{~K}\). If the temperature is raised to $$20 \...

The plane of a dip circle is set in the geographic meridian and the apparent dip is \(\delta_1\). It is then set in a vertical plane perpendicular to the geographic meridian. The apparent dip angle is \(\delta_2\). The declination $$\theta$...