The strength of a magnetic field inside an air-core cylindrical coil (solenoid) depends on the amount of current flowing through it, the number of turn, and length of the coil.
Formula 1
H = 1,257 x [ (I x n) / L ]
Where:
H is the magnetic Field strength in oersted (Oe)
I is the current flowing through the solenoid in amperes (A)
L is the length of the solenoid in centimeters (cm)
n is the number of turns
Derivated formulas:
Formula 2
I = [ (H x L) / ( 1,257 x n ) ]
Formula 3
L = [ (1,257 x n) / (H x I) ]
Formula 4
n = [ (H x I) / (1,257 x n) ]
Application example:
A 2 ampere current flows through in air-core solenoid formed by 60 turns of wire 3 cm long. Calculate the Field strength created by this solenoid.
Data:
I = 2 A
n = 60
L = 3 cm
H = ?
Applying formula 1:
H = 1,257 x [ (2 x 60) / 3 ]
H = 1,357 x 40 = 50,28 Oe
