We know that loops of electric current, permanent magnets, and astronomical objects have a magnetic moment. The magnetic strength and orientation of an object or a magnet that creates a magnetic field are defined by the magnetic moment. We know that loops of electric current, permanent magnets, and astronomical objects have a magnetic moment. In this article, let us know in detail about the magnetic moment.
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What Is Magnetic Moment?
Magnetic moment, also known as magnetic dipole moment, is the measure of the object’s tendency to align with a magnetic field.
βMagnetic Moment is defined as magnetic strength and orientation of a magnet or other object that produces a magnetic field.β
The magnetic moment is a vector quantity. The objects have a tendency to place themselves in such a way that the magnetic moment vector becomes parallel to the magnetic field lines.
The direction of the magnetic moment points from the south to the north pole of a magnet. The magnetic field created by a magnet is directly proportional to the magnetic moment.
How Is The Magnetic Moment Produced?
The magnetic moment is generated by the following two methods:
- The motion of Electric Charge
- Spin Angular Momentum
How Is Magnetic Moment Measured?
Magnetic moments are typically measured by instruments known as magnetometers. But not all magnetometers are aligned to measure the magnetic moment directly. Some of these devices measure magnetic fields only and from the measured magnetic field, the magnetic moment is measured.
Magnetic Moment Formula:
The magnetic moment is a vector relating torque of an object to the magnetic field. This is mathematically represented as:
| Ο = mΒ Γ B |
Where,
- Ο is the torque acting on the dipole
- m is the magnetic moment
- B is the external magnetic field
Read More: Torque
Magnetic Moment Unit:
In the definition for the current loop, the Magnetic moment is the product of the current flowing and the area,Β M = I A
- So, the unit conferring to this definition is articulated byΒ Amp-m2.
- It can also be suggested in terms of torque and moment. Conferring to that,Β the torque is measured in JoulesΒ (J)Β and the magnetic field is measured in teslaΒ (T)Β and thus the unit isΒ J TΒ -1.
- So, these two units are equivalent to each other and are provided byΒ 1 Amp-m2Β = 1 J TΒ -1.
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What Is Magnetic Dipole Moment?
A Magnetic Dipole comprises two unlike poles of equivalent strength and parted by a small distance.
For instance: The needle of a compass, a bar magnet, etc. are magnetic dipoles. We shall show that a current loop works as a magnetic dipole.
Magnetic Dipole Moment is described as the product of pole strength and the distance between the two poles. he distance between the two poles of a magnet or a magnetic dipole is termed as Magnet Length and is given as 2l.
IfΒ mΒ is the power of any magnetic pole then the magnetic dipole moment of the magnet is signified by the vectorΒ M and it is represented as
The Magnetic dipole moment is a vector and it has a direction from the South Pole of the magnet to the north pole of the magnet, as represented in the figure
Expression for Magnetic Dipole Force:
The force on a magnetic dipole is because of both the poles of the magnet, and we consider the magnetic dipole of a bar magnet and assume that the magnet is kept in an unbroken magnetic fieldΒ B. In that situation, the force on the separate poles is articulated as
- Force on N-pole = mB, along the magnetic field B
- Force on S-pole = mB, opposite to magnetic field B
These forces are equivalent in magnitude, but opposite in direction and they form a parallel couple that rotates the magnet clockwise and creates a net torque on the magnet because of the individual force in a couple; thus we have torque acting on the bar magnet.
ΟΒ = Moment of the couple.
ΟΒ = mBΒ ΓΒ 2l sinΒ ΞΈ
WhereΒ ΞΈΒ is the angle between the magnetic axis of the bar magnet and the magnetic field.
Now, from the above discussion, we know that
M = m x 2L
Thus, magnetic dipole moment is articulated by
ΟΒ = MB sinΒ ΞΈ
In vector form, it can be rephrased as:
This is the required expression for the magnetic dipole force.
Read More: Magnetic Dipole Moment
Magnetic Moment Questions
What is theΒ magnetic moment spin formula?
Following is the magnetic moment spin formula:
\(\begin{array}{l}\sqrt{n(n+2)}\end{array} \) |
Where n is the number of unpaired electrons.
What is the magnetic moment of Mn2+ ion?
Mn2+ ion has 5 unpaired electrons. By using magnetic moment for spin formula
What is the magnetic moment of Ni2+ ion?
Ni2+ ion has 2 unpaired electrons. By using magnetic moment for spin formula
What is the magnetic moment of a bar magnet?
Consider a bar magnet of length l and with magnetic moment m. Bend the bar magnet in the form of a semicircular magnet, then the new magnetic moment will be:
\(\begin{array}{l}m’=\frac{2m}{\pi }\end{array} \) |
What is the magnetic moment of an electron?
An electron has a magnetic moment due to its orbital motion and is given as:
\(\begin{array}{l}\frac{\mu _{B}}{2 }\end{array} \) |
Read More: Bar Magnet
Frequently Asked Questions β FAQs
What is a Magnetic Moment?
Is magnetic moment scalar or vector?
How is magnetic moment produced?
What is the magnetic dipole moment?
When is the magnetic moment zero?
What is the formula to calculate the magnetic moment?
How is the magnetic momentum generated?
The motion of electric charge
Spin angular momentum
State true or false: The magnetic field created by a magnet is directly proportional to the magnetic moment.
Define magnetic dipole moment.
In which direction does the direction of the magnetic moment point?
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