Component of magnetic flux density - huh?

[allok]

hiya

If 'b' is the length of a wire, and 'I' current running trough it, then if put a wire inside magnetic field ( not perpendicullary and also not parallel to magnetic field lines, but some angle in between the two ), then magnetic force on a wire will be:

F = I * b * B * sin[angle]

where

I ... current
B ... magnetic flux density

B * sin[angle] gives us component of magnetic flux density perpendicular to current in a wire. I'd understand if we were talking about component of velocity or component of force, but how can we talk about component of density? It just doesn't make sense.thank you

 

[berkeman]

It's the component of flux density, kind of like a wind density for propellers or something. The flux density tells you how much flux is passing through an area, which you use to calculate the induced EMF.

 

[allok]

It makes sense if we are talking about component of velocity of force, but it doesn't make sense that density would also have a component. Density is just density, and by my ( flawed ) logic it can't have a direction. Can someone reason with my how a density can have a component?

 

[berkeman]

It's the density of the magnetic flux lines per unit area. So the lines have the directionality aspect, and the "number" of lines per unit area is the density aspect. Like this picture:

http://www.ee.surrey.ac.uk/Teaching/Courses/EFT/dynamics/html/magnetic_flux.html