List of top Physics Questions on Magnetism and matter

A long cylindrical conductor with large cross section carries an electric current distributed uniformly over its cross-section. Magnetic field due to this current is:
[A.] maximum at either end of the conductor
[B.] maximum at the axis of the conductor and minimum at the midpoint
[C.] minimum at the surface of the conductor
[D.] minimum at the axis of the conductor
[E.] same at all points in the cross-section of the conductor
Choose the correct answer from the options given below:

A plane electromagnetic wave is moving in free space with velocity \[ c=3\times10^{8}\ \text{m/s} \] and its electric field is given as \[ \vec E = 54\sin(kz-\omega t)\,\hat{j}\ \text{V/m}, \] where $\hat{j}$ is the unit vector along the $y$-axis. The magnetic field $\vec B$ of the wave is:

An inductor stores $16\,\text{J}$ of magnetic field energy and dissipates $32\,\text{W}$ of thermal energy due to its resistance when an alternating current of $2\,\text{A}$ (rms) and frequency $50\,\text{Hz}$ flows through it. The ratio of inductive reactance to resistance is _______. $(\pi=3.14)$ Given: \[ U=16\,\text{J},\quad P=32\,\text{W},\quad I=2\,\text{A},\quad f=50\,\text{Hz} \]

A current-carrying coil is placed in an external uniform magnetic field. The coil is free to turn in the magnetic field. What is the net force acting on the coil? Obtain the orientation of the coil in stable equilibrium. Show that in this orientation the flux of the total field (field produced by the loop + external field) through the coil is maximum.

A coil of 60 turns and area $ 1.5 \times 10^{-3} \, \text{m}^2 $ carrying a current of 2 A lies in a vertical plane. It experiences a torque of 0.12 Nm when placed in a uniform horizontal magnetic field. The torque acting on the coil changes to 0.05 Nm after the coil is rotated about its diameter by 90°. Find the magnitude of the magnetic field.

A current of $ \frac{10}{\pi} $ A is maintained in a circular loop of radius 14 cm. The value of dipole moment associated with the loop is:

A long straight wire is held vertically and carries a steady current in upward direction. The shape of magnetic field lines produced by the current-carrying wire are :

A diamagnetic substance is brought, one by one, near the north pole and the south pole of a bar magnet. It is:

Differentiate between magnetic flux through an area and magnetic field at a point.

How will the magnetic field inside a long solenoid be affected when:
(i) the radius of the turns of the solenoid is increased,
(ii) the length of the solenoid as well as the total number of its turns are doubled?

The relationship between the magnetic susceptibility $ \chi $ and the magnetic permeability $ \mu $ is given by:
$ \mu_0 $ is the permeability of free space and $ \mu_r $ is relative permeability.

Given below are two statements : one is labelled as Assertion (A) and the other is labelled as Reason (R)
Assertion (A) : Magnetic monopoles do not exist.
Reason (R) : Magnetic field lines are continuous and form closed loops.
In the light of the above statements, choose the most appropriate answer from the options given below :

Given below are two statements : one is labelled as Assertion A and the other is labelled as Reason R.
Assertion A : If oxygen ion (O$^{-2}$) and Hydrogen ion (H$^{+}$) enter normal to the magnetic field with equal momentum, then the path of O$^{-2}$ ion has a smaller curvature than that of H$^{+}$.
Reason R : A proton with same linear momentum as an electron will form a path of smaller radius of curvature on entering a uniform magnetic field perpendicularly.
In the light of the above statements, choose the correct answer from the options given below

A magnetic dipole experiences a torque of $ 80\sqrt{3} $ N m when placed in a uniform magnetic field in such a way that the dipole moment makes an angle of $ 60^\circ $ with the magnetic field. The potential energy of the dipole is:

A loop ABCD, carrying current $ I = 12 \, \text{A} $, is placed in a plane, consists of two semi-circular segments of radius $ R_1 = 6\pi \, \text{m} $ and $ R_2 = 4\pi \, \text{m} $. The magnitude of the resultant magnetic field at center O is $ k \times 10^{-7} \, \text{T} $. The value of $ k $ is ______ (Given $ \mu_0 = 4\pi \times 10^{-7} \, \text{T m A}^{-1} $)

A 4.0 cm long straight wire carrying a current of 8A is placed perpendicular to an uniform magnetic field of strength 0.15 T. The magnetic force on the wire is ______ mN.

A particle of charge $ q $, mass $ m $, and kinetic energy $ E $ enters in a magnetic field perpendicular to its velocity and undergoes a circular arc of radius $ r $. Which of the following curves represents the variation of $ r $ with $ E $?

The percentage increase in magnetic field $ B $ when space within a current-carrying solenoid is filled with magnesium (magnetic susceptibility $ \chi_{mg} = 1.2 \times 10^{-5} $) is:

A particle of charge 1.6 $\mu$C and mass 16 $\mu$g is present in a strong magnetic field of 6.28 T. The particle is then fired perpendicular to magnetic field. The time required for the particle to return to original location for the first time is _______ s. (Take $ \pi = 3.14 $)

Two long parallel wires X and Y, separated by a distance of 6 cm, carry currents of 5 A and 4 A, respectively, in opposite directions as shown in the figure. Magnitude of the resultant magnetic field at point P at a distance of 4 cm from wire Y is $ 3 \times 10^{-5} $ T. The value of $ x $, which represents the distance of point P from wire X, is ______ cm. (Take permeability of free space as $ \mu_0 = 4\pi \times 10^{-7} $ SI units.)

A bar magnet is held with its length along the axis of a closed coil. Initially, the south pole of the magnet faces the coil. If the magnet is moved towards the coil, explain how a current is induced in the coil and in what direction.

In which case is the potential energy of the magnet minimum?

The magnetic moment (5 J/T) of a bar magnet points along a uniform magnetic field 0.4 T.

Identify the correct statement:

Define the magnetic moment of a current-carrying coil. Write its SI unit.