# Magnetic Dipole Moment of a bar magnet

• akhila_k
In summary, the magnetic dipole moment of a bar magnet is always defined in relation to the torque it would feel in an external field. This is because it is its most observable characteristic and simpler to define. The torque is the result of applying an external field, as explained in the Hyperphysics link.
akhila_k
A bar magnet will have a definite magnetic dipole moment, irrespective of the presence of an external field. Why is the moment, then, always defined in relation to the torque it would feel in an external field? Is there any other definition for the same?

jim hardy said:
you might digest these articles

Thank you. But I still can't get it for a bar magnet.

akhila_k said:
Why is the moment, then, always defined in relation to the torque it would feel in an external field? Is there any other definition for the same?

That is its most readily observable characteristic, its tendency to align with an external field. Think Boy Scout Compass needle...

So why not use that to describe its strength?

According to these guys
https://www.chegg.com/homework-help/definitions/magnetic-dipoles-2
its definition is simpler, and Torque is the result of applying an external field.

as explained in that earlier Hyperphysics link.

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## 1. What is a magnetic dipole moment?

A magnetic dipole moment is a measure of the strength of a magnetic field created by a magnet. It is a vector quantity, meaning it has both magnitude and direction.

## 2. How is the magnetic dipole moment of a bar magnet calculated?

The magnetic dipole moment of a bar magnet is calculated by multiplying the strength of the magnetic field by the area of the magnet's cross-section and the distance between the magnet's poles.

## 3. What is the unit of measurement for magnetic dipole moment?

The unit of measurement for magnetic dipole moment is ampere-meter squared (A·m²) in SI units. In cgs units, it is measured in ergs per gauss (erg·G).

## 4. How does the magnetic dipole moment of a bar magnet affect its strength?

The magnetic dipole moment of a bar magnet directly affects its strength. The larger the dipole moment, the stronger the magnetic field and the more force it can exert on other magnetic objects.

## 5. Can the magnetic dipole moment of a bar magnet be changed?

Yes, the magnetic dipole moment of a bar magnet can be changed by altering its physical properties, such as its size, shape, or material composition. It can also be changed by exposing the magnet to external magnetic fields.

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