# What is Magnetic field on the axis of a current carring circular coil?

A current circulating in a hollow copper coil (solenoid) produces a magnetic field equal to the permeability times the turns density times the current.

B = μ x n x I

* B is the magnetic field measured in Tesla

* μ is the relative permeability of the solenoid's core which is air in this example and have a value approximated to 1.25663706E-6

* n is the turns density which equals the number of turns divided by the solenoid length

n = N/L where L is measured in meters.

* I is the current flowing within the solenoid and measured in Amperes