Magnetic Effects of Current — JEE Main PYQs

The magnetic moment of an electron (e) revolving in an orbit around nucleus with an orbital angular momentum is given by :

Two concentric circular loops of radii $r_1=30$ cm and $r_2=50$ cm are placed in X-Y plane as shown in the figure. A current $I=7$ A is flowing through them in the direction as shown in figure. The net magnetic moment of this system of two circular loops is approximately :

A velocity selector consists of electric field $\vec{E}=E\hat{k}$ and magnetic field $\vec{B}=B\hat{j}$ with $B=12$ mT. The value E required for an electron of energy 728 eV moving along the positive x-axis to pass undeflected is :
(Given, mass of electron …

A cyclotron is used to accelerate protons. If the operating magnetic field is 1.0 T and the radius of the cyclotron 'dees' is 60 cm, the kinetic energy of the accelerated protons in MeV will be:
[use …

The electric current in a circular coil of 2 turns produces a magnetic induction ${\mathrm{B}}_1$ at its centre. The coil is unwound and is rewound into a circular coil of 5 turns and the same current produces a magnetic induction ${\mathrm{B}}_2$ at its centre.

The ratio of …

An electron with energy 0.1 keV moves at right angle to the earth's magnetic field of $1\times 10^{-4}{\mathrm{Wbm}}^{-2}$. The frequency of revolution of the electron will be
(Take mass of electron $=9.0\times 10^{-31}\mathrm{kg}$ )

A charge particle is moving in a uniform magnetic field $(2\hat{i}+3\hat{j})T$. If it has an acceleration of $(\alpha \hat{\mathrm{i}}-4\hat{\mathrm{j}})\mathrm{m}/{\mathrm{s}}^2$, then the value of $\alpha$ will be

${\mathrm{B}}_{\mathrm{X}}$ and ${\mathrm{B}}_{\mathrm{Y}}$ are the magnetic field at the centre of two coils X and Y respectively, each carrying equal current. If coil X has 200 turns and 20 cm radius and coil Y has 400 turns and 20 cm radius, the ratio of …

Two parallel, long wires are kept 0.20 m apart in vacuum, each carrying current of x A in the same direction. If the force of attraction per meter of each wire is $2\times 10^{-6}\mathrm{N}$, then the value of x is approximately:

Two long parallel conductors ${\mathrm{S}}_1$ and ${\mathrm{S}}_2$ are separated by a distance 10 cm and carrying currents of 4A and 2A respectively. The conductors are placed along x-axis in X-Y plane. There is a point P located between the conductors (as shown in figure).

A ch …

A deuteron and a proton moving with equal kinetic energy enter into to a uniform magnetic field at right angle to the field. If $r_d$ and $r_p$ are the radii of their circular paths respectively, then the ratio $\frac{r_d}{r_p}$ will be $\sqrt{x}:1$ where x is ______.

A singly ionized magnesium atom (A24) ion is accelerated to kinetic energy 5 keV and is projected perpendicularly into a magnetic field B of the magnitude 0.5 T. The radius of path formed will be ____ cm.

Two long current carrying conductors are placed parallel to each other at a distance of 8 cm between them. The magnitude of magnetic field produced at mid-point between the two conductors due to current flowing in them is $300\mu \mathrm{T}$. The equal current flowing in the two …

Given below are two statements :

Statement I: The electric force changes the speed of the charged particle and hence changes its kinetic energy: whereas the magnetic force does not change the kinetic energy of the charged particle.

Statement II: The electric force accelerates t …

Two 10 cm long, straight wires, each carrying a current of 5A are kept parallel to each other. If each wire experienced a force of $10^{-5}$ N, then separation between the wires is ______ cm.

A charged particle moves along circular path in a uniform magnetic field in a cyclotron. The kinetic energy of the charged particle increases to 4 times its initial value. What will be the ratio of new radius to the original radius of circular path of the charged particle:

A proton and an alpha particle of the same velocity enter in a uniform magnetic field which is acting perpendicular to their direction of motion. The ratio of the circular paths described by the alpha particle and proton is:

A closely wounded circular coil of radius 5 cm produces a magnetic field of $37.68\times 10^{-4}\text{T}$ at its center. The current through the coil is ______ A.
[Given, number of turns in the coil is 100 and $\pi =3.14$]

A wire of length 314 cm carrying current of 14 A is bent to form a circle. The magnetic moment of the coil is ______ A$-{\text{m}}^2$. [Given $\pi =3.14$]

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

Assertion (A) : In an uniform magnetic field, speed and energy remains the same for a moving charged particle.

Reason (R) : Moving charged particle experiences magnetic fo …

The magnetic field at the centre of a circular coil of radius r, due to current I flowing through it, is B. The magnetic field at a point along the axis at a distance $\frac{r}{2}$ from the centre is :

A proton, a deuteron and an $\alpha$-particle with same kinetic energy enter into a uniform magnetic field at right angle to magnetic field. The ratio of the radii of their respective circular paths is :

A long solenoid carrying a current produces a magnetic field B along its axis. If the current is doubled and the number of turns per cm is halved, the new value of magnetic field will be equal to

A long straight wire with a circular crosssection having radius R , is carrying a steady current I. The current I is uniformly distributed across this cross-section. Then the variation of magnetic field due to current I with distance $r(\mathrm{r}<\mathrm{R})$ from its centre …

The fractional change in the magnetic field intensity at a distance ' $r$ ' from centre on the axis of current carrying coil of radius ' $a$ ' to the magnetic field intensity at the centre of the same coil is : (Take $\mathrm{r}<\mathrm{a}$ )

Two short magnetic dipoles m1 and m2 each having magnetic moment of $1{\mathrm{Am}}^2$ are placed at point O and P respectively. The distance between OP is 1 meter. The torque experienced by the magnetic dipole m2 due to the presence of ${\mathrm{m}}_1$ is ______ …

If the maximum value of accelerating potential provided by a radio frequency oscillator is 12 kV. The number of revolution made by proton in a cyclotron to achieve one sixth of the speed of light is _____.
[ …

A coil in the shape of an equilateral triangle of side 10 cm lies in a vertical plane between the pole pieces of permanent magnet producing a horizontal magnetic field 20 mT. The torque acting on the coil when a current of 0.2 A is passed through it and its plane becomes parallel …

A deuteron and an alpha particle having equal kinetic energy enter perpendicularly into a magnetic field. Let $r_d$ and $r_{\alpha }$ be their respective radii of circular path. The value of $\frac{r_d}{r_{\alpha }}$ is equal to:

A coaxial cable consists of an inner wire of radius '$a$' surrounded by an outer shell of inner and outer radii '$b$' and '$c$' respectively. The inner wire carries an electric current ${\mathrm{i}}_0$, which is distributed uniformly across cross-sectional area. The outer shell c …

Magnetic fields at two points on the axis of a circular coil at a distance of 0.05 m and 0.2 m from the centre are in the ratio $8:1$. The radius of coil is

A proton, a deuteron and an $\alpha$ particle are moving with same momentum in a uniform magnetic field. The ratio of magnetic forces acting on them is ____ and their speed is ____ in the ratio.

Two ions of masses 4 amu and 16 amu have charges +2 e and +3 e respectively. These ions pass through the region of constant perpendicular magnetic field. The kinetic energy of both ions is same. Then:

A uniform conducting wire of length is 24 a, and resistance R is wound up as a current carrying coil in the shape of an equilateral triangle of side 'a' and then in the form of a square of side 'a'. The coil is connected to a voltage source $V_0$. The ratio of magnetic moment o …

The magnetic field vector of an electromagnetic wave is given by $B=B_0=\frac{\hat{i}+\hat{j}}{\sqrt{2}}\cos (kz-\omega t)$; where $\hat{i},\hat{j}$ represents unit vector along $x$ and $y$-axis respectively. At $t=0\mathrm{s}$, two electric charges q 1 of …

A current of 1.5 A is flowing through a triangle, of side 9 cm each. The magnetic field at the centroid of the triangle is :
(Assume that the current is flowing in the clockwise direction.)

A coil having N turns is would tightly in the form of a spiral with inner and outer radii 'a' and 'b' respectively. Find the magnetic field at centre, when a current I passes through coil:

A solenoid of 1000 turns per meter has a core with relative permeability 500 . Insulated windings of the solenoid carry an electric current of 5 A . The magnetic flux density produced by the solenoid is: (permeability of free space …

Two ions having same mass have charges in the ratio $1:2$. They are projected normally in a uniform magnetic field with their speeds in the ratio $2:3$. The ratio of the radii of their circular trajectories is :

Figure A and B show long straight wires of circular cross - section ( a and b with $\mathrm{a}<\mathrm{b}$ ), carrying current I which is uniformly distributed across the cross - section. The magnitude of magnetic field $B$ varies with radius $r$ and can be represented as :

There are two infinitely long straight current carrying conductors and they are held at right angles to each other so that their common ends meet at the origin as shown in the figure given below. The ratio of current in both conductor is 1:1. The magnetic field at point $P$ is

A charge $Q$ is moving $d\vec{\ell }$ distance in the magnetic field $\vec{B}$. Find the value of work done by $\vec{B}$.

A proton and an $\alpha$-particle, having kinetic energy ${\mathrm{K}}_{\mathrm{p}}$ and ${\mathrm{K}}_{\alpha }$ respectively, enter into a magnetic field at right angles. The ratio of the radii of trajectory of proton to that of $\alpha$-particle is $2:1$. The ratio of …

A hairpin like shape as shown in figure is made by bending a long current carrying wire. What is the magnitude of a magnetic field at point P which lies on the centre of the semicircle?

Four identical long solenoids A, B, C and D are connected to each other as shown in the figure. If the magnetic field at the centre of A is 3 T ,the field at the centre of C would be: (Assume that the magnetic field is confined with in the volume of respective solenoid).

A loop of flexible wire of irregular shape carrying current is placed in an external magnetic field . Identify the effect of the field on the wire.

Consider a circular coil of wire carrying constant current $I$, forming a magnetic dipole. The magnetic flux through an infinite plane that contains the circular coil and excluding the circular coil area is given by ${\varphi }_i$. The magnetic flux through the area is given by …

A particle of mass $m$ and charge $q$ has an initial velocity $\vec{v}=v_0\hat{j}$. If an electric field $\vec{E}=E_0\hat{i}$ and magnetic field $\vec{B}=B_0\hat{i}$ act on the particle, its speed will double after a time:

Proton with kinetic energy of 1 MeV moves from south the north. It gets an acceleration of $10^{12}\mathrm{m}/{\mathrm{s}}^2$ by an applied magnetic field (west to east). The value of magnetic field: (Rest mass of proton is $1.6\times 10^{-27}\mathrm{kg}$)

A very long wire $ABADMNDC$ is shown in figure carrying current $I$. $AB$ and $BC$ parts are straight, long and at right angle. At $D$ wire forms a circular turn $DMND$ of radius $R$. $AB$, $BC$ parts are tangential to circular turn at $N$ and $D$. Magnetic field at the centre of …