Class 12 Magnetism And Matter CBSE Questions & Answers

In the magnetic meridian of a certain place, the horizontal component of the earth’s magnetic field is 0.26G and the dip angle is \({60^0}\). What is the magnetic field of the earth at this location

A domain in ferromagnetic iron is in the form of a cube of side length \({\rm{1}}\mu {\rm{m}}\). The molecular mass of iron is 55 g/mole and its density is \({\rm{7}}.{\rm{9 g}}/{\rm{c}}{{\rm{m}}^3}\). Assume that each iron atom has a dipole moment of \({\rm{9}}.{\rm{27}} \times {\rm{1}}{0^{-{\rm{24}}}}{\rm{A }}{{\rm{m}}^{\rm{2}}}\). netisation of the domain is

A short bar magnet placed in a horizontal plane has its axis aligned along the magnetic north-south direction. Null points are found on the axis of the magnet at 14 cm from the centre of the magnet. The earth’s magnetic field at the place is 0.36 G and the angle of dip is zero. What is the total magnetic field on the normal bisector of the magnet at the same distance as the null–point (i.e., 14 cm) from the centre of the magnet? (At null points, field due to a magnet is equal and opposite to the horizontal component of earth’s magnetic field.)

A short bar magnet of magnetic moment \({\rm{5}}.{\rm{25 }} \times {\rm{ 1}}{0^{ - {\rm{2}}}}{\rm{J }}{{\rm{T}}^{ - {\rm{1}}}}\) is placed with its axis perpendicular to the earth’s field direction. At what distance from the centre of the magnet, the resultant field is inclined at \({\rm{45}}\) with earth’s field on its normal bisector . Magnitude of the earth’s field at the place is given to be 0.42 G. Ignore the length of the magnet in comparison to the distances involved.

A short bar magnet of magnetic moment \({\rm{5}}.{\rm{25 }} \times {\rm{ 1}}{0^{ - {\rm{2}}}}{\rm{J }}{{\rm{T}}^{ - {\rm{1}}}}\) is placed with its axis perpendicular to the earth’s field direction. At what distance from the centre of the magnet, the resultant field is inclined at \({\rm{45}}\) with earth’s field on its axis. Magnitude of the earth’s field at the place is given to be 0.42 G. Ignore the length of the magnet in comparison to the distances involved.

A Rowland ring of mean radius 15 cm has 3500 turns of wire wound on a ferromagnetic core of relative permeability 800. What is the magnetic field B in the core for a magnetising current of \({\rm{1}}.{\rm{2 A}}?\)

A sample of paramagnetic salt contains \({\rm{2}}.0{\rm{ }} \times {\rm{ 1}}{0^{{\rm{24}}}}\) atomic dipoles each of dipole moment \({\rm{1}}.{\rm{5 }} \times {\rm{ 1}}{0^{ - {\rm{23}}}}{\rm{J }}{{\rm{T}}^{ - {\rm{1}}}}\). The sample is placed under a homogeneous magnetic field of 0.64 T, and cooled to a temperature of 4.2 K. The degree of magnetic saturation achieved is equal to \({\rm{15}}\% \). What is the total dipole moment of the sample for a magnetic field of 0.98 T and a temperature of 2.8 K? (Assume Curie’s law)

A monoenergetic (18 keV) electron beam initially in the horizontal direction is subjected to a horizontal magnetic field of 0.04 G normal to the initial direction. Estimate the up or down deflection of the beam over a distance of 30 cm (\({{\rm{m}}_{\rm{e}}} = {\rm{ 9}}.{\rm{11 }} \times {\rm{ 1}}{0^{ - {\rm{19}}}}{\rm{C}}\)).

A magnetic dipole is under the influence of two magnetic fields. The angle between the field directions is \({60^0}\), and one of the fields has a magnitude of \({\rm{1}}.{\rm{2 }} \times {\rm{ 1}}{0^{ - {\rm{2}}}}{\rm{T}}\). If the dipole comes to stable equilibrium at an angle of \({15^0}\) with this field, what is the magnitude of the other field?

A compass needle free to turn in a horizontal plane is placed at the centre of circular coil of 30 turns and radius 12 cm. The coil is in a vertical plane making an angle of \({45^0}\) with the magnetic meridian. When the current in the coil is 0.35 A, the needle points west to east. Determine the horizontal component of the earth’s magnetic field at the location

A long solenoid with 80 turns of wire per centimeter carries a current of 0.15 A. The wire that makes up the solenoid is wrapped around a solid core of silicon steel \({{\rm{K}}_{\rm{m}}} = {\rm{52}}00\) (The wire of the solenoid is jacketed with an insulator so that none of the current flows into the core.) For a point inside the core, find the magnitude of the magnetic field due to the solenoid current;

A long solenoid with 80 turns of wire per centimeter carries a current of 0.15 A. The wire that makes up the solenoid is wrapped around a solid core of silicon steel \({{\rm{K}}_{\rm{m}}} = {\rm{52}}00\) (The wire of the solenoid is jacketed with an insulator so that none of the current flows into the core.) For a point inside the core, find the magnitude of the total magnetic fields

A long solenoid with 80 turns of wire per centimeter carries a current of 0.15 A. The wire that makes up the solenoid is wrapped around a solid core of silicon steel \({{\rm{K}}_{\rm{m}}} = {\rm{52}}00\) (The wire of the solenoid is jacketed with an insulator so that none of the current flows into the core.) the magnetization inside the core is

Which of the following statements about magnetic field lines true?

According to Gauss’s law for magnetism