Moving Charges and Magnetism

Two coils P and Q each of radius R carry currents I and $\sqrt{8} \mathrm{I}$ respectively in same direction. Those coils are lying in perpendicular planes such that they have a common centre. The magnitude of the magnetic field at the comm...

The magnetic induction along the axis of a toroidal solenoid is independent of

 A current 'I' flows in anticlockwise direction in a circular arc of a wire having $\left(\frac{3}{4}\right)^{\text {th }}$ of circumference of a circle of radius R. The magnetic field ' $B$ ' at the centre of circle is ( $\mu_0=$ permeabil...

An arc of a circle of radius ' $R$ ' subtends an angle $\frac{\pi}{2}$ at the centre. It carries a current $I$. The magnetic field at the centre will be ( $\mu_0=$ permeability of free space)

Magnetic induction produced at the centre of a circular loop of radius ' $R$ ' carrying a current is ' B '. The magnetic moment of the loop is ( $\mu_0=$ permeability of free space)

Two parallel wires separated by distance 'b' are carrying equal current ' $I$ ' in the same direction. The force per unit length of the wire is

The strength of magnetic field at a perpendicular distance ' $x$ ' near a long straight conductor carrying current ' I ' is ' B '. The magnetic field at a distance $\frac{x}{3}$ from straight conductor will be

Three infinite straight wires $\mathrm{A}, \mathrm{B}$ and C carry currents as shown in figure. The resultant force on wire $B$ is directed

An electron is revolving in a circular orbit of radius $r$ in a hydrogen atom. The angular momentum of the electron is L . The relation between dipole moment (m) associated with it, gyromagnetic ratio ( R ) and L is

Two concentric circular coils A and B having radii 20 cm and 10 cm respectively lie in the same plane. The current in coil A is 0.5 A in anticlockwise direction. The current in coil B , so that net magnetic field at the common centre is zer...

Two long straight parallel wires are separated by a distance '2d'. Each wire carries a current 'I' in the same direction. The magnetic field at a point 'P' midway between them is

A boat is moving due east in a region where the earth's magnetic field is $3.6 \times 10^{-5} \mathrm{~N} / \mathrm{Am}$ due north and horizontal. The boat carries a vertical conducting rod 2 m long. If the speed of the boat is $2.00 \mathr...

The magnetic flux near the axis and inside the air core solenoid of length 80 cm carrying current ' I ' is $1.57 \times 10^{-6} \mathrm{~Wb}$. Its magnetic moment will be [cross-sectional area of a solenoid is very small as compared to its ...

An infinitely long straight conductor carrying current 'I' is bent in a shape as shown in figure. The radius of the circular part of loop is 'r'. The magnetic induction at the centre 'C' is ($\mu=$ permeability of free space)

A current carrying circular loop of radius ' $R$ ' and current carrying long straight wire are placed in the same plane. The current through circular loop and long straight wire are ' $I_c$ ' and ' $\mathrm{I}_{\mathrm{w}}$ ' respectively. ...

Magnetic field at the centre of a circular loop of area ' $A$ ' is ' $B$ '. The magnetic moment of the loop will be

A circular arc of radius r carrying current ' I ' subtends an angle $\frac{\pi}{8}$ at its entre. The radius of a metal wire is uniform. The magnetic induction at the centre of circular arc is ( $\mu_0=$ permeability of free space)

Electron of mass ' $m$ ' and charge ' $q$ ' is travelling with speed ' $v$ ' along a circular path of radius ' $R$ ' at right angles to a uniform magnetic field of intensity ' B '. If the speed of the electron is halved and the magnetic fie...

The magnitude of magnetic field at point 'O' in the following figure will be

A charged particle is moving in a uniform magnetic field in a circular path of radius ' $R$ '. When the kinetic energy of the particle is increased to three times, then the new radius will be

A coil of ' $n$ ' turns and radius ' $R$ ' carries a current 'I'. It is unwound and rewound to make a new coil of radius $\frac{R}{3}$ and the same current is passed through it. The ratio of the magnetic moment of the new coil to that of th...

A long straight wire carrying a current of \(25 \mathrm{~A}\) rests on the table. Another wire PQ of length \(1 \mathrm{~m}\) and mass \(2.5 \mathrm{~g}\) carries the same current but in the opposite direction. The wire PQ is free to slide ...

The magnetic field at a point \(\mathrm{P}\) situated at perpendicular distance '\(R\)' from a long straight wire carrying a current of \(12 \mathrm{~A}\) is \(3 \times 10^{-5} \mathrm{~Wb} / \mathrm{m}^2\). The value of '\(\mathrm{R}\)' in...

10 A current is flowing in two straight parallel wires in the same direction. Force of attraction between them is \(1 \times 10^{-3} \mathrm{~N}\). If the current is doubled in both the wires the force will be

Two circular coils made from same wire but radius of \(1^{\text {st }}\) coil is twice that of \(2^{\text {nd }}\) coil. If magnetic field at their centres is same then ratio of potential difference applied across them is ($$1^{\text {st }}...

A solenoid of length \(0.4 \mathrm{~m}\) and having 500 turns of wire carries a current \(3 \mathrm{~A}\). A thin coil having 10 turns of wire and radius \(0.1 \mathrm{~m}\) carries current \(0.4 \mathrm{~A}\). the torque required to hold t...

A straight wire carrying a current (I) is turned into a circular loop. If the magnitude of the magnetic moment associated with it is '\(M\)', then the length of the wire will be

A horizontal wire of mass '\(m\)', length '\(l\)' and resistance '\(R\)' is sliding on the vertical rails on which uniform magnetic field '\(B\)' is directed perpendicular. The terminal speed of the wire as it falls under the force of gravi...

A long wire is bent into a circular coil of one turn and then into a circular coil of smaller radius having \(\mathrm{n}\) turns. If the same current passes in both the cases, the ratio of magnetic fields produced at the centre for one turn...

Figure shows two semicircular loops of radii \(R_1\) and \(R_2\) carrying current $I$. The magnetic field at the common centre '\(\mathrm{O}\)' is

Two concentric circular coils A and B have radii \(20 \mathrm{~cm}\) and \(10 \mathrm{~cm}\) respectively lie in the same plane. The current in coil A is \(0.5 \mathrm{~A}\) in anticlockwise direction. The current in coil B so that net fiel...

A circular coil of radius '\(r\)' and number of turns ' $n$ ' carries a current '\(I\)'. The magnetic fields at a small distance '\(h\)' along the axis of the coil \(\left(B_a\right)\) and at the centre of the coil $$\left(\mathrm{B}_{\math...

A circular current carrying coil has radius \(R\). The magnetic induction at the centre of the coil is \(B_C\). The magnetic induction of the coil at a distance \(\sqrt{3} R\) from the centre along the axis is \(B_A\). The ratio $$B_A: B_C$...

The ratio of magnetic field at the centre of the current carrying circular loop and magnetic moment is \(X\). When both the current and radius are doubled, then the ratio will be

A single turn current loop in the shape of a right angle triangle with side \(5 \mathrm{~cm}, 12 \mathrm{~cm}, 13 \mathrm{~cm}\) is carrying a current of \(2 \mathrm{~A}\). The loop is in a uniform magnetic field of magnitude $$0.75 \mathrm...

Two similar coils each of radius \(\mathrm{R}\) are lying concentrically with their planes at right angles to each other. The current flowing in them are I and 2I. The resultant magnetic field of induction at the centre will be $$\left(\mu_...

The magnetic moment of a current (I) carrying circular coil of radius '\(r\)' and number of turns '\(n\)' depends on

\(\mathrm{A}, \mathrm{B}\) and \(\mathrm{C}\) are three parallel conductors of equal lengths and carry currents I, I and 2I respectively as shown in figure. Distance \(A B\) and \(B C\) is same as '\(d\)'. If '\(F_1\)' is the force exerted ...

An electron makes a full rotation in a circle of radius \(0.8 \mathrm{~m}\) in one second. The magnetic field at the centre of the circle is \(\left(\mu_0=4 \pi \times 10^{-7}\right.\) SI units)

A coil of '\(n\)' turns and radius '\(R\)' carries a current '\(I\)'. It is unwound and rewound again to make another coil of radius \(\left(\frac{\mathrm{R}}{3}\right)\), current remaining the same. The ratio of magnetic moment of the new ...

Two concentric circular coils of 10 turns each are situated in the same plane. Their radii are \(20 \mathrm{~cm}\) and \(40 \mathrm{~cm}\) and they carry respectively \(0.2 \mathrm{~A}\) and \(0.3 \mathrm{~A}\) current in opposite direction...

An electron is projected along the axis of circular conductor carrying current I. Electron will experience

Two parallel wires of equal lengths are separated by a distance of \(3 \mathrm{~m}\) from each other. The currents flowing through \(1^{\text {st }}\) and \(2^{\text {nd }}\) wire is \(3 \mathrm{~A}\) and 4.5 A respectively in opposite dire...

A cylindrical magnetic rod has length \(5 \mathrm{~cm}\) and diameter \(1 \mathrm{~cm}\). It has uniform magnetization \(5.3 \times 10^3 \mathrm{~A} / \mathrm{m}^3\). Its net magnetic dipole moment is nearly

A circular arc of radius '\(r\)' carrying current '\(\mathrm{I}\)' subtends an angle \(\frac{\pi}{16}\) at its centre. The radius of a metal wire is uniform. The magnetic induction at the centre of circular arc is \(\left[\mu_0=\right.\) pe...

Two long conductors separated by a distance '\(\mathrm{d}\)' carry currents \(I_1\) and \(I_2\) in the same direction. They exert a force '\(F\)' on each other. Now the current in one of them is increased to two times and its direction is r...

Electron of mass '\(\mathrm{m}\)' and charge '\(\mathrm{q}\)' is travelling with speed '\(v\)' along a circular path of radius '\(R\)', at right angles to a uniform magnetic field of intensity '\(B\)'. If the speed of the electron is halved...

Two long parallel wires carrying currents \(8 \mathrm{~A}\) and \(15 \mathrm{~A}\) in opposite directions are placed at a distance of \(7 \mathrm{~cm}\) from each other. A point '\(\mathrm{P}\)' is at equidistant from both the wires such th...

Two wires \(2 \mathrm{~mm}\) apart supply current to a \(100 \mathrm{~V}, 1 \mathrm{~kW}\) heater. The force per metre between the wires is ( \(\mu_0=4 \pi \times 10^{-27}\) SI unit)

The magnetic field at the centre of a circular coil of radius '\(R\)', carrying current \(2 A\) is '\(B_1\)'. The magnetic field at the centre of another coil of radius '\(3 R\)' carrying current \(4 A\) is '\(B_2\)'. The ratio \(B_1:B_2\) ...