The magnetic field generated by the coil is given by its inductance (geometry of the coil) and flowing current. For the solenoid coil, the inductance is given by:

\[ L = μ{\frac{N^{2}S}{l}} \]

where µ is the permeability of the environment inside of the coil (could be air or yoke to increase the magnetic field generated by the coil), N is the number of windings, S is the cross-section area of the coil and l is its length.

l
m
S
m2
N
-
μ
H/m

L
H

Then magnetic field generated by the current I flowing through the coil is:

\[ B = {\frac{L.I}{NS}} \]