Finding a Unknown Inductor Equation

Discussion in 'Homework Help' started by trav, Dec 13, 2011.

1. trav Thread Starter New Member

Dec 8, 2011
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0
Does anybody know the formula to calculate for a unknown inductor?

2. t06afre AAC Fanatic!

May 11, 2009
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Can you elaborate on the problem 3. trav Thread Starter New Member

Dec 8, 2011
7
0
Well I've got the formula F = 1 / 2pi sqrt L x C
and need rearrange to find L but dont really know if my answer is correct.

4. trav Thread Starter New Member

Dec 8, 2011
7
0
I got the formula of L = 1 / 4(pi^2)(f^2)xC anyone can clarify this?

5. thatoneguy Expert

Feb 19, 2009
6,349
732
Is this for a simple, air core inductor with a single winding?

Or to determine the Fo of an LC circuit?

I see both your formulas have f and C in your equations. I must admit I do not understand the question you are asking.

There is a formula for a wound air coil of Length L and diameter d with a winding density factor.

There is a formula for an inductor wound on a ferrite core, but the permiability of the core would be needed.

The resonant frequency,

Please be more verbose with your question, explaining what you do know, and what you'd like to figure out.

First, keep in mind: and

--ETA: Your Post #3 states you want to solve

The equation is derived from:

to get L out, we need to square both sides:

now we can "swap" the left with the denominator

woops, moved one too many:

Obviously, the formula is the same to find C if you know f and L

Last edited: Dec 14, 2011
6. debjit625 Well-Known Member

Apr 17, 2010
790
186
@trav
I also didn't understood your question...
Anyway to find out inductance for a coil you can use Wheeler's Formula

where
N = number of turns
A = average coil radius
B = coil length
C = coil thickness

Note
All quantities are in inches and the result is in microhenries .

Good Luck

7. Adjuster Late Member

Dec 26, 2010
2,147
303
The OP's problem appears to be stated in terms of the resonant frequency in a tuned circuit, not the coil's construction.