I know the weight of a external magnetic object, how could I calculate the coil turns to lift that object?
It depends on magnetic flux density of magnet core, it's size and distance to the object.
So my first question is, how would I most easily go about calculating magnetism on a coil?
For a seed, let's take a simple single layer solenoid with the following parameters:
N - coil turns count
w - coil length (meters)
D - coil diameter (meters)
n = N / w = winding density (turns per meter)
The solenoid is connected to the electric current source with the following parameters:
I - current (Amps)
Now let's calculate magnetic field strength H and magnetic flux density B:
H = n * I [Amps/m]
B = µ0*µ * H * w/sqrt(4 * (D/2)^2 + w^2) [Tesla]
where
µ0 = 1.25664e-06 [H/m] (magnetic permeability of free space constant)
µ = 1 (relative magnetic permeability of solenoid core, for air=1)
And how would I determine how much impedance for the coil to perform that?
First lets calculate inductance, it is more complicated, you can estimate it with this formula:
L = (µ0*µ * D * (N^2)/2)*(ln(1+(pi*D/(2*w)))+(1/(2.3004+3.437*(w/D)+1.7636 * (w/D)^2 - (0.47/((0.755+D/w)^1.44))))) [H]
Now you can calculate reactance:
X = 2 * pi * f * L [Ω]
where
f = frequency (Hz)
Impedance also needs wire AC resistance. In order to calculate it, you're needs to take into account skin effect at frequency f. I'm not sure how to calculate it properly for a coil, so let's try to approximate it with a straight wire.
Rac = ρ * h / Aeff [Ω]
where
h = pi * D * N [meters] (wire length)
ρ = 1/σ [Ω/m] (resistivity of the conductor)
σ = 5.96e7 [S/m] (conductivity of the conductor, for Copper=5.96e7)
Aeff = δ * pi * d [m^2] (effective cross sectional area of wire used at frequency f)
d = diameter of the conductor [meters]
δ = sqrt( ρ / (pi * f * µ0*µc) ) [meters] (nominal depth of penetration for a conductor at frequency f)
µc = 0.999994 [H/m] (relative magnetic permeability of the conductor, for Copper=0.999994)
Now you have impedance of the coil:
Z = Rac + jX [Ω]
If you just want to estimate coil resistance for DC current, you can do it a little easier:
Rdc = ρ * h / A [Ω]
A = pi * (d/2)^2 [m^2] (cross-sectional area of wire)
How can I calculate where the coil saturation point is?
Saturation is not a coil property, this is a property of core material and you're needs to check material datasheet to get magnetic flux density for saturation.