List of top Physics Questions on Magnetic Effects of Current and Magnetism

The strongest force among the following forces in nature is

A current loop of magnetic moment $ 0.5 \, \text{Am}^2 $ is placed in a magnetic field of $ 0.4 \, \text{T} $. If the loop is rotated from an angle of $ 0^\circ $ to $ 180^\circ $, what is the change in potential energy?}

Two long straight conductors carrying equal current kept parallel at a separation of $d$ metre experience a force per unit length. If the distance of separation is made $2d$, then to maintain the same force per unit length on each conductor, the current in each conductor should be increased to

If \( H = \dfrac{\varepsilon^r E^p x^q}{t^s} \) find \(p, q, r\) and \(s\). \[ H \rightarrow \text{Magnetic field} \] \[ \varepsilon \rightarrow \text{Permittivity of medium} \] \[ E \rightarrow \text{Electric field} \] \[ x \rightarrow \text{distance} \] \[ t \rightarrow \text{time} \]

A 5 mg particle carrying a charge of \(5\pi \times 10^{-6}\) C is moving with velocity of \((3\hat{i} + 2\hat{k}) \times 10^{-2}\) m/s in a region having magnetic field \(\vec{B} = 0.1 \hat{k}\) Wb/m². It moves a distance of \(a\) meter along \(\hat{k}\) when it completes 5 revolutions. The value of \(a\) is ________.

A current carrying circular loop of radius 2 cm with unit normal \(\hat{n} = \frac{\hat{k} + \hat{i}}{\sqrt{2}}\) is placed in a magnetic field, \(\vec{B} = B_0 (3\hat{i} + 2\hat{k})\). If \(B_0 = 4 \times 10^{-3}\) T and current \(I = 100\sqrt{2}\) A, the torque experienced by the loop is ________ Wb·A.

A current of \(30\,\text{A}\) each flows in opposite directions in two conducting wires, placed parallel to each other at a distance of \(8\,\text{cm}\). The magnetic field at the mid point between the two wires is _____ \(\mu\text{T}\). \(\left(\frac{\mu_0}{4\pi}=10^{-7}\,\text{}^2\right)\)

The charged particle moving in a uniform magnetic field of \((3\hat{i} + 2\hat{j}) \text{ T}\) has an acceleration \((4\hat{i} - \frac{x}{2}\hat{j}) \text{ m/s}^2\). The value of \(x\) is ____.

A circular coil of radius 2 cm and 125 turns carries a current of 1 A. The coil is placed in a uniform magnetic field of magnitude 0.4 T. The axis of the coil makes an angle of \( 30^\circ \) with the direction of the magnetic field. The torque acting on the coil is \( \alpha \times 10^{-4} \text{ N.m} \). The value of \( \alpha \) is _______. (\( \pi = 3.14 \))

A particle having charge \( 10^{-9} \, \text{C} \) moving in \( x \)-\( y \) plane in fields of \( 0.4 \hat{j} \, \text{N/C} \) and \( 4 \times 10^{-3} \hat{k} \, \text{T} \) experiences a force of \( \left( 4 \hat{i} + 2 \hat{j} \right) \times 10^{-10} \, \text{N} \). The velocity of the particle at that instant is _______ m/s.

A \(1\,\mu\text{C}\) charge moving with velocity} \[ \vec{v} = (\hat{i} - 2\hat{j} + 3\hat{k}) \, \text{m/s} \] in the region of magnetic field} \[ \vec{B} = (2\hat{i} + 3\hat{j} - 5\hat{k}) \, \text{T} \] The magnitude of force acting on it is \( \sqrt{\alpha} \times 10^{-6} \) N. The value of \(\alpha\) is ____.}

Two identical long current carrying wires are bent into the shapes shown. If the magnitude of magnetic fields at the centres \(P\) and \(Q\) of a semicircular arc are \(B_1\) and \(B_2\) respectively, then the ratio \( \dfrac{B_1}{B_2} \) is:

The energy of an electron in an orbit of the Bohr's atom is $-0.04 E_g$ where $E_g$ is the ground state energy. If $L$ is the angular momentum of the electron in this orbit and $h$ is the Planck's constant, then $\frac{2 \pi L{h}$ is _________} :}

The current passing through a conducting loop in the form of equilateral triangle of side $4\sqrt{3}$ cm is 2 A. The magnetic field at its centroid is $\alpha \times 10^{-5}$ T. The value of $\alpha$ is ___. (Given : $\mu_0 = 4\pi \times 10^{-7}$ SI units)

Two small balls with masses m and 2m are attached to both ends of a rigid rod of length d and negligible mass. If angular momentum of this system is L about an axis (A) passing through its centre of mass and perpendicular to the rod then angular velocity of the system about A is:

There are three long parallel wires in a plane as shown. Find the force on \(15\) cm of length of the middle wire.

A particle carrying a charge equal to 1000 times the charge on an electron, is rotating one rotation per second in a circular path of radius '$r$' m. If the magnetic field produced at the centre of the path is $x$ times the permeability of vacuum, the radius '$r$' in m is $[e = 1.6 \times 10^{-19} \text{C}] \quad [x = 2 \times 10^{-16}]$

A long wire carrying a steady current is bent into a circle of single turn. The magnetic field at the centre of the coil is ' $\text{B}$ '. If it is bent into a circular loop of radius ' $\text{r}_1$ ' having ' $\text{n}$ ' turns, the magnetic field at the centre of the coil for same current is

A wire has three different sections as shown in figure. The magnitude of the magnetic field produced at the centre '\(O\)' of the semicircle by three sections together is ( \(\mu_0 =\) permiability of free space)

The wire loop $PQRSP$ formed by joining two semicircular wire of radii $R_1$ and $R_2$ carries a current $I$ as shown. The magnitude of the magnetic field at the centre ' O ' is

A circular coil of wire consisting of ' $n$ ' turns each of radius $8\text{ cm}$ carries a current of $0.4\text{ A}$ . The magnitude of the magnetic field at the centre of coil is $3.14 \times 10^{-4}\text{ T}$. The value of ' $n$ ' is [Take $\mu_0 = 12.56 \times 10^{-7}\text{ SI unit}$]}

A particle carrying a charge equal to 1000 times the charge on an electron, is rotating one rotation per second in a circular path of radius '$r$' m. If the magnetic field produced at the centre of the path is $x$ times the permeability of vacuum, the radius '$r$' in m is $[e = 1.6 \times 10^{-19} \text{C}] \quad [x = 2 \times 10^{-16}]$

(I) Write Ampere’s circuital law in mathematical form and explain the terms used.
(II) As the current-carrying solenoid is made longer, the magnetic field produced outside it approaches zero. Why?
(III) A flexible loop of irregular shape carrying current, when located in an external magnetic field, changes to a circular shape. Give reason.