# Re: Medhurst Table

```Antinio, Mike, and Reinhard,

Thanks for the equations. They were exactly what I was looking for.
Regarding accuracy, all faired well, even Mikes "h/d above 2 calculation".
I personally have chosen Reinhard's equation because it was easy to
incorporate in my spreadsheet with forth order accuracy (may as well be as
accurate as possible - it's just as easy for excel).

For reference and consolidation, I willl paste the equations given.

Thanks guys,
Bart

>From Antonio:
capacitance=(11.26*L+16*R+76.4*sqrt(R*R*R/L))*1e-12

From: Mike
K = 0.100976*(H/D) + 0.309630
If you want K for the entire series including (H/D) less that two, it
becomes a forth order equation.
K = 0.0005x^4 - 0.0097x^3 + 0.0648x^2 - 0.0757x + 0.4723

From: Reinhard
K = (.585-.25442*(H/D)+(.15563*(H/D)^2)-(.02777*(H/D)^3)+(.00172*(H/D)^4))
Use H/D values in cm unless converting to cm at the Cself equation.

(for reference)
Medhurst formula: C = K * D
C = solenoid self-capacitance in picofarads
D = diameter of solenoid in centimeters
K = (originally) extracted from the Medhurst table of h/d ratio's
Cself(pF) = K * (D * 2.54) <<<converting at the Cself equation

```