Magnetism and matter practice · Medium

The correct measure of magnetic hardness of a material is

A magnetic needle suspended by a silk thread is vibrating in the earth's magnetic field. if the temperature of the needle is increased by $700^{\circ} \mathrm{C}$, then

The unit for molar susceptibility is

To made temporary magnet, magnetic material should have

If $\tau_1, \tau_2, \tau_3$ and $\tau_4$ are the magnetic torques acting on the bar magnet when it is kept at angles of $30^{\circ}, 60^{\circ}, 90^{\circ}$ and $135^{\circ}$ respectively with the direction of the magnetic field, then which among the following is correct?

A magnetic dipole is under the influence of two magnetic fields making an angle ${45^\mathrm{o}}$ between them. One of the fields has magnitude $2.828 \times {10^{ - 2}}T$. If the dipole comes to stable equilibrium with the above field at an angle of ${30^\mathrm{o}}$ then the other magnetic field is

Assertion (A): For making permanent magnets, steel is preferred over soft iron.

Reason (R): As retantivity of steel is smaller.

Given below are two statements:
Statement-I: Susceptibilities of paramagnetic and ferromagnetic substances increase with decrease in temperature.
Statement-II: Diamagnetism is a result of orbital motions of electrons developing magnetic moments opposite to the applied magnetic field.
Choose the correct answer from the options given below:-

Assertion (A): To protect any instrument from external magnetic field, it is put inside an iron box.

Reason (R): Iron is a ferro magnetic substance.

Two magnets of magnetic moments $m$ and $\sqrt{3} m$ are joined to form a cross (+). The combination is suspended freely in a uniform magnetic field. In equilibrium position, the magnet of magnetic moment $m$ makes an angle $\theta$ with the field. Find $\theta$.

Which of the following statement is true for
relative magnetic permeability?

If a diamagnetic solution is poured into a U-tube and one arm of this U-tube is placed between the poles of a strong magnet, with the meniscus in line with the field, then the level of solution will

Select the incorrect statement:

Two long bar magnets are placed with their axes coinciding in such a way that the north pole of the first magnet is $2.0 \mathrm{~cm}$ from the south pole of the second. If both the magnets have a pole strength of $10 \mathrm{Am}$, find the force exerted by one magnet on the other.

The absolute permeability is $8\pi \times {10^{ - 6}}\,H/m$. Its relative permeability is

The torque on a bar magnet due to the earth’ magnetic field is maximum when the axis of the magnet is

A thin magnetic needle is placed in a magnetic field of $200 \mathrm{G}$ with its axis at $30^{\circ}$ to the direction of the field. find the magnetic moment of the needle if it experience a torque of ${0 . 0 1 2}$ $\mathrm{Nm}$ in this field.

All atoms of a magnetic substance have a
resultant magnetic moment even in absence of
external magnetic field. The substance is

Assertion (A): A compass needle which is allowed to move in a horizontal plane is taken to a geomagnetic pole. It will stay in any direction.

Reason (R): At geomagnetic pole $B_H=0$.

Angle between magnetic meridian and geographical meridian is called

The period of oscillation of a magnet in vibration magnetometer is $2 \mathrm{~s}$. The period of oscillation of a magnet whose magnetic moment is four times that of first magnet is

The angle of dip at a place is$37^\circ$ and the vertical component of the earth’s magnetic field is $6 \times {10^{ - 5}}\mathrm{\;T}.$ The earth’s magnetic field at this place is $(\mathrm{tan\;}37^\circ = 3/4$)

At the magnetic north pole of the earth, the value of the horizontal component of earth’s magnetic field and angle of dip are respectively

Assertion(A): The poles of magnet cannot be separated by breaking into two pieces.

Reason(R): The magnetic moment will be reduced to half when a magnet is broken into two equal pieces.

A small quantity of paramagnetic liquid is
taken in a watch – glass and kept on two
dissimilar magnetic poles. The liquid

If a diamagnetic material is placed in a
magnetic field, the flux density inside the
material compared to that outside will be:

Two short bar magnets of moments $512 \mathrm{~Am}^2$ and $1000 \mathrm{~Am}^2$ are placed coaxially $18 \mathrm{~cm}$ apart. The magnetic field is zero are point $Q$ between them. The field at $Q$, when one of the magnets is reversed pole to pole is

A compass needle which is allowed to move in a horizontal plane is taken to a geomagnetic pole. It

The susceptibility of certain magnetic material is 400. What is the class of magnetic material?

Magnetic intensity for an axial point due to a short bar magnet of magnetic moment $M$ is given by