Flux density and flux problem.

[alternativess]

The question is like this,

Find the flux density and flux in each of the outer limbs and the central limbs.
http://img394.imageshack.us/img394/1627/4441sa.jpg

Below is the diagram of the question.
http://img210.imageshack.us/img210/8559/q49rs.jpg


I know that Flux Density = Flux lines/unit area.
But, I don't have idea about the outer limbs and the central limbs.
I am confused.
I would appreaciate if expert could guide me about this question.

Four more days left to my final exam. But still searching method to do this question.

[mdshunk]

Here's my best effort, but it's been too long to know if I'm right...

B=F/I*L

B being flux density, F being force in newtons, I of course being current, and L being the length in meters. Restated:

B=1000/.5*L

L is different for each limb, measured along the mean flux path. Restated again:

B=1000/.5*.82 meters (for red and purple limbs)
B=1000/.5*.815 meters (for green and yellow flux paths)

Solved:
B=2439 Teslas for red, purple
B=2452 Teslas for green, yellow

My answers can't be right, since there's nothing that can have a flux density over maybe 15 or 20 teslas, and the iron would get hot enough to melt down on itself. I need to think on this some more. I also don't have the air core or air gaps or reactance plugged in, or cross sectional area of the iron in there anywhere. This is a big *** problem the more I think about it....

[Speedy Petey]

Not having been through this type of schooling, can someone tell me just what the hell this has to do with electrical contracting? Even remotely???

Maybe if someone was looking to be an EE I can see the point.

[suemarkp]

I'd say it doesn't, but it does apply to EE exams. I was kind of shocked to learn in school that you learn all this theory stuff with circuits that make no sense. They say find the current here, the voltage there, and the flux over here. You work with "ideal" components at the undergraduate level.

So when you get a BSEE, you still can't design working things worth a crap because all you know about is ideal components, which you can't buy. I knew more about how to build stuff before I went to college. Surprisingly, this how the schooling system is supposed to work...

[Homer]

I've been away for a while so this may be too late to help the original poster. :cry:

Using assumption (a) with the relative permeability or the core being infinite, the problem is manageable for an old timer like myself. Using assumption (b) with the relative permeability of the core being 4500, the problem becomes 'big assed' as MD has said.

For case (a) it is electrically analogous to a single supply with no source resistance and two parallel loads.

So we have a magnetic source instead with an MMF = 500 Amp-turns

The permeability of free space is 1.2566x10-6 Wb/A.m

Reluctance of left or right branch = length of air gap / (perm x area)

Reluctance of center = zero as per assumption (a)

Flux = MMF / Reluctance

Flux left = 0.00157 Weber

Flux right = 0.000785 Weber

Flux center = Flux right + Flux left = 0.002355 Weber

Flux Density = Flux / Area

Flux Density left = 0.628 Tesla

Flux Density right = 0.314 Tesla

Flux Density center = 0.471 Tesla

Now if you need to calculate this magnetic circuit with the reluctance of the three core segments it becomes more than I'm willing to solve here. :D

Homer