# How to find the total number of turns needed to produce a flux..?

Discussion in 'Homework Help' started by sama3505, Jun 11, 2016.

1. ### sama3505 Thread Starter New Member

Jun 10, 2016
18
0
Consider the magnetic circuit shown. Assume that the reluctance of the iron is small enough to be ignored. For an air gap of 0.1 cm, and an effective area of each gap of 10 cm2, determine the TOTAL number of turns needed to produce a flux density of 0.5 T in the gaps.

•Consider the coil shown on slide 7. Make up reasonable numbers and determine the magnetic field in the gap and on the pole face. Consider the force on a current carrying wire placed in the gap.

•Calculate the energy needed to produce a field of 1 T over a volume big enough to put a person in (like you would find in an MRI).

•What is the typical magnetic field saturation in silicon steel?

•Look up the current carrying capacity of a 12 gauge wire (<40 oC rise). And convert this to A/m2.

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2. ### wayneh Expert

Sep 9, 2010
12,368
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Homework, perhaps?
Hint: The field strength in the gap depends very strongly on the length of the gaps. As noted in the question, the higher permeability of the iron dwarfs the low permeability of the air gap.

3. ### DGElder Member

Apr 3, 2016
347
87
Sama, you need to show your attempt to solve the problem and as specific questions with respect to that attempt.

Jun 10, 2016
18
0
ok

5. ### MrAl Distinguished Member

Jun 17, 2014
2,542
512

Hello there,

There are several questions there, and i noticed right away one which would be answerable by someone with at least a modest experience with magnetic constructions used in electrical and electronics areas. I would think that they would be asked only of persons who had at least a little experience or course work, or are allowed to research in various forums and literature without limit except maybe within a certain time frame, but i wont be so presumptuous just yet.
So, are you saying that you have no idea how to do any of these questions, or do you just have to answer one of them?
I ask so that i could better understand what you are seeking here.

6. ### sama3505 Thread Starter New Member

Jun 10, 2016
18
0
I want to know the steps for the all questions which were asked in that..So i can work it out

7. ### MrAl Distinguished Member

Jun 17, 2014
2,542
512
•Consider the coil shown on slide 7. Make up reasonable numbers and determine the magnetic field in the gap and on the pole face. Consider the force on a current carrying wire placed in the gap.

•Calculate the energy needed to produce a field of 1 T over a volume big enough to put a person in (like you would find in an MRI).

•What is the typical magnetic field saturation in silicon steel?

•Look up the current carrying capacity of a 12 gauge wire (<40 oC rise). And convert this to A/m2.

I repeated your questions above for convenience.

First a couple questions for you.

1. Do you know how to find the diameter and area of a 12 gauge wire?
2. Do you know how to find data sheets on magnetic materials like si steel?
3. Do you have any idea what "reasonable numbers" are in that question?