More Electromagnetics

[murphyslabrat]

For a copper coil, is there a linear relationship between the increase of power and the strengthening of the field, and if so, does it depend on the length of the coil?

So, assuming I had three feet of 24 AWG copper wrapped into a 1-inch diameter coil, how much power would I need to have a 1-pound pull-force?

 

[polarbear6]

i didnt read ur post i just read the title
i think we can derive this with amprees law
some b X intgral of area = u0i => b = u0.i/2.pie.r
now that we have the b
force = qvb

 

[CycloWizard]

This would be a good place to start. Once you know the induced field strength, it's straightforward to calculate the total induced force, which is given by F=BL*I=mu*2*pi*R*N*I, where R is the average coil radius, N is the total number of turns (i.e. 2*pi*R*N=length of coil wire), mu is the permeability of what you're moving, and I is the current.

edit: failed at teh linking

 

[KIAman]

When you talking about field, I assume you are talking about electromagnetic field and not electric field.

The strength of your electromagnet is directly proportional to the number of turns (coils) and the current (amps). The proportion is almost linear (not linear because of the condition of the core and air gap and composition, flux leakage, etc.).

To calculate how much power you need to have 1 pound of force, you'll need to give the following.

a. The core material's permeability
b. Total length of the magnetic field (core + air gap) (you gave)
c. Number of turns of the wire
d. Cross sectional area of the core (you gave)
e. Distance of the force to measure (drops off at a ratio of inverse square of distance)

Then, you can apply the equation (using the references above)

I (current) = (Force * 8pi(10^-7) * b^2) / a^2 * c^2 * d