JEE Magnetism & Magnetic Materials PYQs with Video Solutions PDF

In a uniform magnetic field, the magnetic needle has a magnetic moment $$9.85 \times 10^{-2}$$ A m$$^{-2}$$ and moment of inertia $$5 \times 10^{-6}$$ kg m$$^2$$. If it performs 10 complete oscillations in 5 seconds then the magnitude of the magnetic field is _________ mT [Take $$\pi^2$$ as 9.85]

An electron and a proton having the same kinetic energy enter a region of uniform magnetic field $$B$$ acting perpendicular to their velocity vectors. Let $$r_e$$ and $$r_p$$ be the radii of their circular paths respectively. If the mass of the proton is approximately $$1800$$ times the mass of the electron ($$m_p \approx 1800 \, m_e$$), the ratio of their radii $$\frac{r_p}{r_e}$$ is:

The magnetic field of earth at the equator is approximately $$4 \times 10^{-5}$$ T. The radius of earth is $$6.4 \times 10^6$$ m. Then the dipole moment of the earth will be nearly of the order of:

A magnetic compass needle oscillates 30 times per minute at a place where the dip is 45° and 40 times per minute where the dip is 30°. If B$$_1$$ and B$$_2$$ are the net magnetic fields due to the earth at the two places respectively, then the ratio B$$_1$$/B$$_2$$ is approximately equal to

A paramagnetic substance in the form of a cube with sides 1 cm has a magnetic dipole moment of $$20 \times 10^{-6}$$ J/T when a magnetic intensity of $$60 \times 10^3$$ A/m is applied. Its magnetic susceptibility is:

The value of aluminium susceptibility is $$2.2 \times 10^{-5}$$. The percentage increase in the magnetic field if space within a current carrying toroid is filled with aluminium is $$\frac{x}{10^4}$$. Then the value of $$x$$ is ___.

An iron rod of volume $$10^{-3}\,\text{m}^3$$ and relative permeability 1000 is placed as core in a solenoid with 10 turns $$\text{cm}^{-1}$$. If a current of $$0.5\,\text{A}$$ is passed through the solenoid, then the magnetic moment of the rod will be:

The vertical component of the earth's magnetic field is $$6 \times 10^{-5}$$ T at any place where the angle of dip is 37°. The earth's resultant magnetic field at that place will be (Given tan 37° = 3/4)

In a ferromagnetic material, below the curie temperature, a domain is defined as:

At an angle of 30$$^\circ$$ to the magnetic meridian, the apparent dip is 45$$^\circ$$. Find the true dip:

Two bar magnets oscillate in a horizontal plane in earth's magnetic field with time periods of $$3 \text{ s}$$ and $$4 \text{ s}$$ respectively. If their moments of inertia are in the ratio of $$3:2$$ then the ratio of their magnetic moments will be

At a certain place the angle of dip is 30° and the horizontal component of earth's magnetic field is 0.5 G. The earth's total magnetic field (in G), at that certain place, is

The space inside a straight current carrying solenoid is filled with a magnetic material having magnetic susceptibility equal to $$1.2 \times 10^{-5}$$. What is fractional increase in the magnetic field inside solenoid with respect to air as medium inside the solenoid?

The coercivity of a magnet is $$5 \times 10^3$$ A/m. The amount of current required to be passed in a solenoid of length 30 cm and the number of turns 150, so that the magnet gets demagnetised when inside the solenoid is _____ A.

A coil of 200 turns and area $$0.20 \text{ m}^2$$ is rotated at half a revolution per second and is placed in uniform magnetic field of 0.01 T perpendicular to axis of rotation of the coil. The maximum voltage generated in the coil is $$\frac{2\pi}{\beta}$$ volt. The value of $$\beta$$ is ______.

In Young's double slit experiment, carried out with light of wavelength $$5000 \text{ \AA}$$, the distance between the slits is $$0.3 \text{ mm}$$ and the screen is at $$200 \text{ cm}$$ from the slits. The central maximum is at $$x = 0 \text{ cm}$$. The value of $$x$$ for third maxima is ______ mm.

The earth's magnetic field lines resemble that of a dipole at the centre of the earth. If the magnetic moment of this dipole is close to $$8 \times 10^{22}$$ Am$$^2$$, the value of earth's magnetic field near the equator is close to (radius of the earth = $$6.4 \times 10^6$$ m)

An alpha particle and a proton are accelerated from rest through the same potential difference $$V$$. They both then enter a region of uniform magnetic field $$B$$ moving perpendicular to the direction of the field. Find the ratio of the radii of their circular paths, $$\frac{r_\alpha}{r_p}$$.

A magnetic needle is kept in a non-uniform magnetic field. It experiences

A 25 cm long solenoid has the radius 2 cm and 500 turns. It carries a current of 15 A. If it is equivalent to a magnet of the same size and magnetization $$\vec{M}$$ $$\left(\frac{\text{Magnetic Moment}}{\text{volume}}\right)$$, then $$|\vec{M}|$$ is:

A paramagnetic material has $$10^{28}$$ atoms m$$^{-3}$$. Its magnetic susceptibility at temperature 350 K is $$2.8 \widetilde{A} \times 10^{-4}$$. Its susceptibility at 300 K is

Following plots show Magnetization (M) vs Magnetising field (H) and Magnetic susceptibility ($$\chi$$) vs Temperature (T) graph:

Which of the following combination will be represented by a diamagnetic material?

The magnetic potential due to a magnetic dipole at a point on its axis situated at a distance of $$20$$ cm from its center is $$1.5 \times 10^{-5}$$ T m. The magnetic moment of the dipole is _______ A m$$^2$$. (Given: $$\frac{\mu_0}{4\pi} = 10^{-7}$$ T m A$$^{-1}$$)

A bar magnet is demagnetized by inserting it inside a solenoid of length 0.2 m, 100 turns, and carrying a current of 5.2 A. The coercivity of the bar magnet is:

Two short bar magnets of length 1 cm each have magnetic moments 1.20 A m$$^2$$ and 1.00 A m$$^2$$ respectively. They are placed on a horizontal table parallel to each other with their N poles pointing towards the south. They have a common magnetic equator and are separated by a distance of 20.0 cm. The value of the resultant horizontal magnetic induction at the mid-point O of the line joining their centres is close to
(Horizontal component of earth's magnetic induction is $$3.6 \times 10^{-5}$$ Wb m$$^{-2}$$)

The magnetic susceptibility of a material of a rod is 499. Permeability in vacuum is $$4\pi \times 10^{-7}$$ Hm$$^{-1}$$. Absolute permeability of the material of the rod is:

The magnetic moment of a bar magnet is $$0.5$$ Am$$^2$$. It is suspended in a uniform magnetic field of $$8 \times 10^{-2}$$ T. The work done in rotating it from its most stable to most unstable position is:

A conductor of length $$l$$ is placed perpendicular to a horizontal uniform magnetic field $$B$$. Suddenly, a certain amount of charge is passed through it, when it is found to jump to a height $$h$$. The amount of charge that passes through the conductor is

A magnet hung at $$45°$$ with magnetic meridian makes an angle of $$60°$$ with the horizontal. The actual value of the angle of dip is

The hysteresis loop for a soft iron core is narrower than that of a carbon steel core. Which of the following properties is correct for soft iron over carbon steel based on this fact?