Magnetic Effects of Current — JEE Main PYQs

An infinitely long straight wire carrying current I is bent in a planer shape as shown in the diagram. The radius of the circular part is r . The magnetic field at the centre O of the circular loop is :

The current passing through a conducting loop in the form of equilateral triangle of side $4\sqrt{3}\mathrm{cm}$ is 2A. The magnetic field at its centroid is $\alpha \times 10^{-5}\mathrm{T}$. The value of $\alpha$ is ____.
(Given : …

Three long straight wires carrying current are arranged mutually parallel as shown in the figure. The force experienced by 15 cm length of wire $Q$ is ______.
(${\mu }_0=4\pi \times 10^{-7}\mathrm{T}.\mathrm{m}/\mathrm{A}$)

The magnetic field at the centre of a current carrying circular loop of radius $R$ is $16\mu \mathrm{T}$. The magnetic field at a distance $x=\sqrt{3}R$ on its axis from the centre is ____ $\mu \mathrm{T}$.

Two identical circular loops P and Q each of radius r are lying in parallel planes such that they have common axis. The current through P and Q are I and 4I respectively in clockwise direction as seen from O. The net magnetic field at O is:

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 ends of the conductor and minimum at the midpoint
B. maximum at the axis of the conductor
C …

A current carrying is placed vertically and a particle of mass m with charge Q is released from rest. The particle moves along the axis of solenoid. If g is acceleration due to gravity then the acceleration (a) of the charged particle will satisfy :

A particle having charge $10^{-9}\mathrm{C}$ moving in $x-y$ plane in fields of $0.4\hat{\mathrm{j}}\mathrm{N}/\mathrm{C}$ and $4\times 10^{-3}\hat{k}\mathrm{T}$ experiences a force of $(4\hat{i}+2\hat{j})\times 10^{-10}\mathrm{N}$. The velocity of the part …

An insulated wire is wound so that it forms a flat coil with N=200 turns. The radius of the innermost turn is $r_1=3$ cm, and of the outermost turn $r_2=6$ cm. If 20 mA current flow in it then the magnetic moment will be $\alpha \times 10^{-2}$ A.m${}^2$. The value of $\alpha$ is _ …

Two identical small bar magnets each of dipole moment $3\sqrt{5}\mathrm{J}/\mathrm{T}$ are placed at a center to center separation of 10 cm , with their axes perpendicular to each other as shown in figure. The value of magnetic field at the point P midway between the magnets …

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 …

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

A particle of charge $q$ and mass $m$ is projected from origin with an initial velocity $\vec{v}=\left(\frac{v_0}{\sqrt{2}}\hat{\mathrm{x}}+\frac{v_0}{\sqrt{2}}\hat{\mathrm{y}}\right)$. There exists a uniform magnetic field $\vec{B}=B_0\hat{\mathrm{z}}$ and a spa …

A current of 30 A each flows in opposite directions in two conducting wires, placed parallel to each other at a distance of 8 cm. The magnetic field at the mid point between the two wires is ______ $\mu \mathrm{T}$. …

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, $\overrightarrow{\mathrm{B}}={\mathrm{B}}_0(3\hat{\mathrm{i}}+2\hat{\mathrm{k}})$. If ${\mathrm{B}}_0=4\times 10^{-3}\mathrm{T}$ and cur …

A 5 mg particle carrying a charge of $5\pi \times 10^{-6}\mathrm{C}$ is moving with velocity of $(3\hat{\mathrm{i}}+2\hat{\mathrm{k}})\times 10^{-2}\mathrm{m}/\mathrm{s}$ in a region having magnetic field …

Two identical long current carrying wires are bent into the shapes shown in the following figures. If the magnitude of magnetic fields at the centres P and Q of a semicircular arc are ${\mathrm{B}}_1$ and ${\mathrm{B}}_2$ respectively, then the ratio $\frac{B_1}{B_2}$ is ____ …

$1\mu \mathrm{C}$ charge moving with velocity $\overrightarrow{\mathrm{v}}=(\hat{\mathrm{i}}-2\hat{\mathrm{j}}+3\hat{\mathrm{k}})\mathrm{m}/\mathrm{s}$ in the region of magnetic field $\vec{B}=(2\hat{i}+3\hat{j}-5\hat{k})$ T. The magnitude of force acting on it is …

An electron projected perpendicular to a uniform magnetic field B moves in a circle. If Bohr's quantization is applicable, then the radius of the electronic orbit in the first excited state is :

A proton is moving undeflected in a region of crossed electric and magnetic fields at a constant speed of $2\times 10^5{\mathrm{ms}}^{-1}$. When the electric field is switched off, the proton moves along a circular path of radius 2 cm . The magnitude of electric field is …

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 …

The magnetic field inside a 200 turns solenoid of radius 10 cm is $2.9\times 10^{-4}$ Tesla. If the solenoid carries a current of 0.29 A , then the length of the solenoid is $\_\_\_\_$ $\pi \mathrm{cm}$.

Consider a long straight wire of a circular cross-section (radius a) carrying a steady current I. The current is uniformly distributed across this cross-section. The distances from the centre of the wire's cross-section at which the magnetic field [inside the wire, outside the wi …

An infinite wire has a circular bend of radius a, and carrying a current $I$ as shown in figure. The magnitude of magnetic field at the origin O of the arc is given by :

Consider a long thin conducting wire carrying a uniform current I. A particle having mass "M" and charge "q" is released at a distance "a" from the wire with a speed ${\mathrm{v}}_o$ along the direction of current in the wire. The particle gets attracted to the wire due to magnet …

Given below are two statements. One is labelled as Assertion (A) and the other is labelled as Reason(R).
Assertion (A) : A electron in a certain region of uniform magnetic field is moving with constant velocity in a straight line path.
Reason (A) : The magnetic field in that regi …

N equally spaced charges each of value q , are placed on a circle of radius R . The circle rotates about its axis with an angular velocity $\omega$ as shown in the figure. A bigger Amperian loop B encloses the whole circle where as a smaller Amperian loop A encloses a small segme …

A tightly wound long solenoid carries a current of 1.5 A. An electron is executing uniform circular motion inside the solenoid with a time period of 75 ns . The number of turns per metre in the solenoid is ______.
[Take mass of electron …

A current of 5A exists in a square loop of side $\frac{1}{\sqrt{2}}\mathrm{m}$. Then the magnitude of the magnetic field B at the centre of the square loop will be $p\times 10^{-6}\mathrm{T}$. where, value of $p$ is $\_\_\_\_$ .
$[$ Take …

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

A loop ABCDA , carrying current $\mathrm{I}=12\mathrm{A}$, is placed in a plane, consists of two semi-circular segments of radius ${\mathrm{R}}_1=6\pi \mathrm{m}$ and ${\mathrm{R}}_2=4\pi \mathrm{m}$. The magnitude of the resultant magnetic field at center O is …

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

Given below are two statements: one is labelled as Assertion A and the other is labelled as Reason R.

Assertion A: If oxygen ion (${\text{O}}^{-2}$) and Hydrogen ion (${\text{H}}^{+}$) enter normal to the magnetic field with equal momentum, then the path of ${\text{O}}^{-2}$ ion …

Uniform magnetic fields of different strengths ($B_1$ and $B_2$), both normal to the plane of the paper exist as shown in the figure. A charged particle of mass m and charge q, at the interface at an instant, moves into the region 2 with velocity $v$ and returns to the interface. …

A particle of charge q, mass m and kinetic energy E enters in 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 $E$?

Figure shows a current carrying square loop ABCD of edge length is 'a' lying in a plane. If the resistance of the ABC part is r and that of ADC part is $2r$, then the magnitude of the resultant magnetic field at centre of the square loop is

Let $B_1$ be the magnitude of magnetic field at center of a circular coil of radius R carrying current I. Let ${\mathrm{B}}_2$ be the magnitude of magnetic field at an axial distance 'x' from the center. For …

A solid/long straight wire of circular cross-section with radius 'a' carries a steady current I uniformly distributed across the cross-section. The plot of magnitude of magnetic field B with distance r from the centre of the wire is given by: [graph options in source]

A coil having 100 turns, area of $5\times 10^{-3}{\mathrm{m}}^2$, carrying current of 1 mA is placed in uniform magnetic field of 0.20 T such a way that plane of coil is perpendicular to the magnetic field. The work done in turning the coil through $90^{\circ }$ is ______ …

Two parallel long current carrying wire separated by a distance 2 r are shown in the figure. The ratio of magnetic field at A to the magnetic field produced at C is $\frac{\mathrm{X}}{7}$. The value of x is ____.

An electron is projected with uniform velocity along the axis inside a current carrying long solenoid. Then :

The magnetic field existing in a region is given by $\overrightarrow{\mathrm{B}}=0.2(1+2\mathrm{x})\hat{\mathrm{k}}\mathrm{T}$. A square loop of edge 50 cm carrying 0.5 A current is placed in $\mathrm{x}-\mathrm{y}$ plane with its edges parallel to the $x-y$ axes, as sho …

The electrostatic force $({\overrightarrow{\mathrm{F}}}_1)$ and magnetic force ( ${\overrightarrow{\mathrm{F}}}_2$ ) acting on a charge q moving with velocity v can be written :

A solenoid of length 0.5 m has a radius of 1 cm and is made up of 'm' number of turns. It carries a current of 5 A. If the magnitude of the magnetic field inside the solenoid is $6.28\times 10^{-3}$ T, then the value of m is :

In a co-axial straight cable, the central conductor and the outer conductor carry equal currents in opposite directions. The magnetic field is zero.

A 2A current carrying straight metal wire of resistance $1\Omega$, resistivity $2\times 10^{-6}\Omega \mathrm{m}$, area of cross-section $10{\mathrm{mm}}^2$ and mass 500 g is suspended horizontally in mid air by applying a uniform magnetic field …

An element $\Delta l=\Delta \mathrm{x}\hat{\mathrm{i}}$ is placed at the origin and carries a large current $\mathrm{I}=10\mathrm{A}$. The magnetic field on the y-axis at a distance of 0.5 m from the elements $\Delta \mathrm{x}$ of 1 cm length is :

A circular coil having 200 turns, $2.5\times 10^{-4}{\text{ m}}^2$ area and carrying $100\mu \text{A}$ current is placed in a uniform magnetic field of 1 T. Initially the magnetic dipole moment ($\vec{M}$) was directed along $\vec{B}$. Amount of work, required to rotate t …

An electron with kinetic energy 5 eV enters a region of uniform magnetic field of $3\mu \mathrm{T}$ perpendicular to its direction. An electric field E is applied perpendicular to the direction of velocity and magnetic field. The value of E, so that electron moves along the sam …

A long straight wire of radius a carries a steady current I. The current is uniformly distributed across its cross section. The ratio of the magnetic field at $\frac{\mathrm{a}}{2}$ and 2 a from axis of the wire is :