the flux density through a solenoid is given by
[tex]B=\mu_o n I[/tex]
Where n is the number of turns per unit length.
The number of field lines per unit area is proportional to B.
I am assuming that at or near the centre of the solenoid the number of field lines per unit area decreases so B decreases.
If that is true, then how come the formula stated above doesn't account for distance from the centre of the solenoid?