The length of the solenoid (l) is 80 cm (0.8 m).
On the solenoid, there are five levels of windings, each with 400 turns.
∴ Total number of solenoid rotations, N = 5 x 400 = 2000
Diameter of the solenoid (D) = 1.8 cm = 0.018 m
The current carried by the solenoid (I) is equal to 8.0 A.
The following is the relationship that determines the magnitude of the magnetic field within the solenoid at its centre:
$B = \frac{{{\mu _o}NI}}{l}$
Where,
${\mu _o} = $Permeability of free space
${\mu _o} = 4\pi \times {10^{ – 7}}Tm{A^{ – 1}}$
$B = \frac{{4\pi \times {{10}^{ – 7}} \times 2000 \times 8}}{{0.8}}$
$B = 2.5 \times {10^{ – 2}}T$
As a result, the magnitude of B within the solenoid at its centre is $2.5 \times {10^{ – 2}}T$.