Magnet

The magnetic moment of a circular orbit of radius 'r' carrying a charge 'q' and rotating with velocity v is given by

$Q$ charge is uniformly distributed over the curve surface of a right circular cone of semi-vertical angle $\theta$ and height $h$. The cone is uniformly rotated about its axis at angular velocity $\omega$. Calculate associated magnetic dipole moment. $(h>R)$

If $r$ is the orbital radius and $v$ is the orbital velocity of an electron in a hydrogen atom, then its magnetic dipole moment is

The magnetic moment of the current carrying loop shown in the figure is equal to

A short bar magnet has a magnetic moment of$0.65 \mathrm{J} {\mathrm{T}}^{-1}$ then the magnitude and direction of the magnetic field produced by the magnet at a distance $8 \mathrm{cm}$ from the centre of magnet on the axis is

The characteristics of two coils are given below:

If the magnetic moments of both coils $A$ and $B$ are equal, choose the correct relation.

A steel wire of length $l$ and magnetic moment $M$ is bent into a semicircular arc of radius $R$. The new magnetic moment is

The net dipole moment of the system as shown in the figure is

A bar magnet of length $10 \mathrm{cm}$ and pole strength $20 \mathrm{A}-\mathrm{m}$ is deflected through $30°$ from the magnetic meridian. If earth's horizontal component field is $\frac{320}{4\pi }\mathrm{A} {\mathrm{m}}^{-1}$. The moment of the deflecting couple is

A thin bar magnet of length $L$ and magnetic moment $M$ is bent at the midpoint so that the two parts are at right angles. The new magnetic length and magnetic moment are respectively

An $\mathrm{L}$ shaped bar magnet is converted into a straight bar magnet. It is found that the change in the magnetic moment is $40\%$. The original shape of the bar magnet was-

Here it is known to us that $y>x$. Later the shape of the bar magnet is like this

Calculate the ratio $\frac{y}{x}$.

What is the magnitude of the equatorial fields due to a bar magnet of length $5.0 \mathrm{cm}$ at a distance $75 \mathrm{cm}$ from its mid point? The magnetic moment of the bar magnet is $0.75 \mathrm{A} {\mathrm{m}}^2$.

The neutral points on the equatorial line were found to be at $0.2 \mathrm{m}$ from the centre of a short-bar magnet. The horizontal component of earths magnetic field induction is $0.39\times {10}^{-4}$Tesla. If ${\mu }_0=4\pi \times {10}^{-7}$ Henry/$\mathrm{m}$, the magnetic moment of the short-bar-magnet is

A bar magnet of magnetic moment $M$ is bent to form a semicircle. What is the magnetic moment of the bent magnet?

A compass needle just above a wire in which electrons are moving towards east, will point

The magnetic field lines due to a bar magnet are correctly shown in

A bar magnet was divided into three parts.

$A$ thin bar magnet oscillates with a time period $T.$ If it is cut into two equal pieces along its axis, time period of oscillation of each piece is

A uniform magnetic field exists in space in the plane of paper and is initially directed from left to right. When a bar of soft iron is placed in the field parallel to it, the lines of force passing through it will be represented by:

A magnetic wire of dipole moment $4\mathrm{\pi } \mathrm{A} {\mathrm{m}}^2$ is bent in the form of semicircle. The new magnetic moment is