# Inductance of a solenoid

1. Nov 25, 2008

### ElectroPhysics

I have to make a solenoid to operate some device. Can anybody let me know what formula to use to calculate number of turns for a solenoid wound on some metal. I also want to calculate the force.

Does this formula works

B = uourNI/L
&
F = ILB

2. Nov 26, 2008

### Mayura

what you are using is for long distance solenoid

I have seen one more formula

B=UoUrNI(CosPhi1-Cosphi2)/2l

3. Nov 26, 2008

### ElectroPhysics

Here is the procedure that I have used to find out the DC solenoid

v = IR where R is the Dc resistance of solenoid and V is the applied voltage
R = V/I
from here I can find out the wire lenght, L from wire table

now

F = ILB where F is the weight that solenoid can raise without letting it to fall and L is length of solenoid
or
B = F/IL from here I can calculate B

also B = uourNI/L

or N = BL/uourI from here I can calculate number of turns

and inductance = uourN2A/L where A is the cross section area.

The problem is that if we also consider the inner and outer dia of solenoid and we use some metal material then this crosssection area A correspond to which area. also tell me if F= ILB is the right equation if I want to see how much weight in newton the solenoid can raise if I insert some steel etc object inside solenoid and attach weight F = mg to it and it does not fall down.

Last edited: Nov 26, 2008