Basic Math

1. Oct 15, 2008

burnit

Hi,

This is not homework, i'm just confused:

I have been asking on the electrical engineering forum about calculating the strength of electromagnets.

After some searching i have found the equations but i just can't quite get a handle on some of it?

They have an iron core C shaped electromagnet 15cm long & 1cm square in area.

They write: The reluctance of the air gap is 1 centimeter divided by 1 times 1 square centimeter.

The answer they have is 100 henries per meter.

How do they calculate this to get 100 as the answer?

Thanks

2. Oct 15, 2008

burnit

I forgot to add that the air gap is 1cm & the permeability of air is 1 in this example.

Thanks

3. Oct 15, 2008

burnit

Ok, i'll have a go at it, the equation is:

(1 centimeter) / (1 * 1 (square centimeter)) = 100 m-1

I noticed that Reluctance is in Henries per Meter but the above calculation is in Centimeters so i assume the answers i have been getting are actually Henries per Centimeter, do i simply multiply the answer by 100 to change it to meters & then the answer is in Henries per meter & seem correct?.