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Magnetic flux in spool.

  • Thread starter Mutaja
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  • #1
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Homework Statement



The attached picture shows a spool coil on a iron core with an air gap measuring 2.5mm. The spool is coiled by 0.5mm2 with rho cu = 0.0175 Ωmm2 /m. The average winding diameter for the spool is 3.18cm.

Compute the magnetic flux in the spool.

attachment.php?attachmentid=67961&stc=1&d=1395681020.png

Homework Equations





The Attempt at a Solution



Using the equation: phi = I * N / Rm, I still miss I, and I have no idea how to compute it. Rm is the reluctance which I can get from a B-H characteristic - if that applies to this problem.

My first questions are these I guess: Is this the correct formula? If yes, how to I compute I?

Any feedback and help is as always greatly appreciated. Thanks.
 

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Answers and Replies

  • #2
rude man
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Your formula is fine but you need to use the correct reluctance.
You also need either the voltage or the current in the spool.

Hint: the reluctance of the air gap is >> reluctance of the rest of the core. Forget B-H of the core!
 
  • #3
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Your formula is fine but you need to use the correct reluctance.
You also need either the voltage or the current in the spool.

Hint: the reluctance of the air gap is >> reluctance of the rest of the core. Forget B-H of the core!
If I need the voltage or current, it would apprear it's missing from the problem - and I do apologize for that. But since you say I can use the voltage, how should I go about it if we set the voltage to 24V?
 
  • #4
rude man
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Per your equation, you need the current, right?
 
  • #5
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Per your equation, you need the current, right?
Yes, but the voltage is given at a later problem, so I figured why not just test it now as I'm not sure what to do. If I have the current, I would just need to plot it + find the correct reluctance to proceed.

I don't know though, it was just an idea.
 
  • #6
rude man
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???

get the current, by hook or by crook!
 

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