The magnetic field intensity ' $\mathrm{H}$ ' at the centre of a long solenoid having ' $n$ ' turns per unit…
The magnetic field intensity ' $\mathrm{H}$ ' at the centre of a long solenoid having ' $n$ ' turns per unit length and carrying a current I', when no material is kept in it, is
$\frac{\mathrm{I}}{\mathrm{n}}$
$\frac{\mathrm{n}}{\mathrm{I}}$
$\mathrm{nI}$
$\mathrm{n}^2 \mathrm{I}$
Solution
nl is the magnetic field intensity at the centre of a long solenoid when no material is kept in it