Magnetic strength cannot be measured

[bobsmith76]

I don't get the following passage from my textbook. Why can't the magnetic force be measured? I don't see why there is no unit for p.

If one pole of a long, thin bar magnet is placed in the vicinity of one pole of another long, thin bar magnet, Coulomb’s magnetic force law states: The magnetic force F between one pole of magnetic strength p1 and another pole of magnetic strength p2 is inversely proportional to the square of the distance r between
them, or F ∝ p1p2/2 . It is not possible, however, to find a proportionality constant, because it is not possible to define a unit for p, a magnetic monopole

 

[Drakkith]

I *think* it's just saying that because there are no magnetic monopoles, which would be an object that is only 1 pole of a magnet, aka a "magnetic charge", we cannot define a constant to it's strength like we can with the electric force, which does have single charges of both positive and negative. Not sure though.

 

[technician]

I would agree with Drakkith. In electricity and gravitation it is possible to define a unit charge and a unit mass but I have never met a definition of a unit magnetic pole.

 

[Meir Achuz]

The magnetic pole strength at the end of a bar magnet equals MA, where M is the magnetization and A the area lof the end in Gaussian units. The unit of pole strength is
gauss-cm^2. The end acts like a point monopole when its area is small compare to r^2.

 

[sardar]

.

I can explain that the reason why the magnetic force cannot be measured is because magnetic monopoles do not exist. Unlike electric charges, which can exist as both positive and negative, magnetic poles always come in pairs - a north and a south pole. This means that there is no way to isolate a single magnetic pole to measure its strength.

In the passage from your textbook, the magnetic force law is mentioned, which relates the force between two magnetic poles to their strengths. However, since there is no way to define a unit for magnetic strength, the proportionality constant cannot be determined. This is due to the fact that the concept of a single, isolated magnetic pole is not possible in nature.

In other words, the magnetic force cannot be measured because it is not possible to isolate and measure the strength of a single magnetic pole. This is a fundamental property of magnetism that has been observed and studied for centuries. While we may not fully understand the underlying reasons for this phenomenon, it is a well-established fact in the field of physics.