Why all the inductance formulas doesn't consider wire diameter.?

Question

Why all the inductance formulas doesn't consider wire diameter.?

Answer 1

If your formula for inductance of a wire doesn't include the diameter, you either don't understand what the formula says or are looking at the wrong formula.  As for the comment that diameter only affects resistance, not inductance --- NOT TRUE!  Do you really think that 1 meter of 1 mm diameter wire has the same inductance as 1 meter of 50 mm diameter wire?  It doesn't.  One of the most widely used formulas for wire inductance is by Frederick Grover.  It uses length and diameter.  Try Googling it.

Answer 2

The Grover formula uses COIL diameter, not WIRE diameter. The wire diameter makes a difference only because you cannot cram as many turns onto the coil if the wire is thicker. But because of this "automatic" effect, it does not need to be included in the formula. Note that these formulas are approximate, you are lucky if you get within 10%.

Answer 3

Only resistance is affected by the wire diameter.

It has no effect on inductance.