# Solenoid force calculation

1. Apr 19, 2014

### Bern123

Hi all, i'm trying to calculate solenoid force using this tool:

http://www.daycounter.com/Calculators/Magnets/Solenoid-Force-Calculator.phtml

I can't understand the ralation with A in the formula and also if this formula takes into account the lenght of solenoid.

I explain better:

If i have a solenoid with 2000 turns inner diameter of 10mm wire diameter of 0.1mm and solenoid lenght of 20mm i have 17.66 mH inductance.
If i have a solenoid with 2000 turns inner diameter of 10mm wire diameter of 0.1mm and solenoid lenght of 10mm i have 31 mH inductance.

I have more layers of wire in 10mm instead in 20mm and the force is higher.

So, this calculator calculate on a single layer? so does not consider the length of solenoid?

I need to calculate on a multiple layer solenoid. There is formula that from Magnetic B-field or Inductance i obtain force on a pice of metal that distant g(stroke)?