Write the equation of magnetic field on the axis of a current-carrying finite solenoid.

(N/A) For a finite solenoid of length $2L$,radius $R$,and $n$ turns per unit length carrying current $I$,the magnetic field $B$ at a point $P$ on its axis at a distance $x$ from the center is given by:
$B = \frac{\mu_0 n I}{2} [\cos \theta_1 + \cos \theta_2]$
Where $\theta_1$ and $\theta_2$ are the angles subtended by the ends of the solenoid at the point $P$ on the axis.
Alternatively,in terms of distance $x$ from the center:
$B = \frac{\mu_0 n I}{2} \left[ \frac{L-x}{\sqrt{R^2 + (L-x)^2}} + \frac{L+x}{\sqrt{R^2 + (L+x)^2}} \right]$