A solenoid 8.6 cm in radius?

Question

A solenoid 8.6 cm in radius and 82 m in length
has 13700 uniformly spaced turns and carries
a current of 3.1 A. Consider a plane circular
surface of radius 1.5 cm located at the center
of the solenoid with its axis coincident with
the axis of the solenoid.
What is the magnetic flux through this
circular surface?(1Wb = 1Tm^2) Answer in
units of Wb.

Answer 1

M-Flux= B A
B- Magnetic induction of magnetic field density
A – Area though which the magnetic flux flows

B = uI (n / l)
I-current
n- number of turns
l – length
u – permittivity of free space (4pi E−7 Newton•/Ampere)

We have

M-Flux= uI (n / l) A=

M-Flux= 4pi E−7 x 3.1 x (13700 / 82) x pi x (.015)^2
M-Flux =1.04e-10 Wb