# Question about magnetic flux density B

• A
Magnetic flux density B is a vector quantity and thus represents a force. However most texts state that the magnetic force is perpendicular to the direction of B, which is tangential to the magnetic field line at any give point. I assume that this magnetic force refers to the Lorentz force. So my question is:

1) What exactly does the direction of force B represent?

2) Would it be correct to state that it is the force B that acts on a test magnet causing it to orient along a magnetic force line?

Dale
Mentor
2020 Award
Magnetic flux density B is a vector quantity and thus represents a force.
This is not correct. Not everything that is a vector represents a force. The B field in particular is not a force.

tech99
This is not correct. Not everything that is a vector represents a force. The B field in particular is not a force.

Yes, I guess that was implied in the first part of the question. So what does the direction of B indicate?

Dale
Mentor
2020 Award
Yes, I guess that was implied in the first part of the question. So what does the direction of B indicate?
It is the direction perpendicular to both the magnetic force and the current.

It is the direction perpendicular to both the magnetic force and the current.

I've already mentioned that in my question! I wish to know what this "direction" of B represents?

Dale
Mentor
2020 Award
That is all it represents. There is only one such line which is perpendicular to both the force and the current, and the B field direction identifies it. That is all, there is no more or less meaning.

That is all it represents. There is only one such line which is perpendicular to both the force and the current, and the B field direction identifies it. That is all, there is no more or less meaning.

Interesting. So, why come up with the concept of direction of the B field at all?

There must be some reason why a test magnet aligns itself in the direction of the B field....