# Difference in these two concepts of Magnetic Torque

• Physicslearner500039
In summary, the concept of torque is handled differently in different books. In one concept, a loop placed in a magnetic field with a current flowing through it experiences a force and torque, while in another concept, a similar loop becomes an electromagnet and experiences a repulsive torque when in the presence of another magnetic field. The two concepts are not the same, and the first one does not mention electromagnets. However, it is possible to think of a current carrying loop in terms of magnetic poles, but this may not be helpful in understanding the concept of torque.
Physicslearner500039
TL;DR Summary
Understanding the difference of magnetic force
I am confused with the concept of Torque handled differently in books,
Concept1: If a loop is placed in a magnetic field and the current flowing in the loop is ##I## there will be force and torque acting on the loop given by ##F = I \vec l \times \vec B ##. The torque is given by ##\tau =\vec \mu \times \vec B ##.
Concept2: If a current flows through the loop then it becomes an electromagnet and a North and South pole are developed and if another magnetic field is present then there will be another North and South pole. The similar poles repel each other and a torque is produced.
Are the two concepts same? Why there is no mention of electromagnet in the concept1? Please advise.

First of all: what is B?

Physicslearner500039
Borek said:
First of all: what is B?
B is magnetic field

Physicslearner500039 said:
B is magnetic field

Electromagnet produces magnetic field, doesn't it?

Physicslearner500039
A current carrying loop has a magnetic moment ##\vec{m} = I\vec{A}##. It is correct that in an external magnetic field a couple ##\vec{\tau} = \vec{m} \times \vec{B}## is exerted on the loop.

If you like, you can think of a magnetic moment equivalently as two opposite magnetic poles of magnitude ##p## separated by a vector ##\vec{l}##, such that$$\vec{m} = p\vec{l}$$This is more natural for e.g. a bar magnet, but I suppose there is nothing stopping you from thinking about the current carrying loop in terms of magnetic poles.

Physicslearner500039 said:
Concept2: If a current flows through the loop then it becomes an electromagnet and a North and South pole are developed and if another magnetic field is present then there will be another North and South pole. The similar poles repel each other and a torque is produced.

Are you saying that, e.g. the external magnetic field is produced by another bar magnet, whose north pole (say) is repelling the effective north pole of the current carrying loop. I suppose that is a fine analogy, but it's probably not really helpful to think of current carrying loops in terms of magnetic poles.

Physicslearner500039

## 1. What is the difference between magnetic torque and torque?

Magnetic torque is a type of torque that is caused by the interaction between a magnetic field and a magnetic dipole, while torque is a general term for the twisting force that causes rotation.

## 2. How do magnetic torque and torque affect objects differently?

Magnetic torque only affects objects that have a magnetic dipole, while torque can affect any object that has a force applied to it causing rotation.

## 3. Are the formulas for calculating magnetic torque and torque the same?

No, the formulas for calculating magnetic torque and torque are different. The formula for magnetic torque involves the magnetic field strength and the angle between the magnetic field and the magnetic dipole, while the formula for torque involves the force applied and the distance from the pivot point.

## 4. Can magnetic torque and torque be applied simultaneously?

Yes, magnetic torque and torque can both be applied to an object at the same time. This can result in a combination of rotational and magnetic motion.

## 5. How are magnetic torque and torque used in real-world applications?

Magnetic torque is commonly used in devices such as electric motors, generators, and compasses. Torque is used in many mechanical systems, such as car engines, bicycles, and door hinges. Both are important concepts in understanding and designing various technologies.

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