Given, number of turns per unit length, n=1000 Relative magnetic permeability, µt=500 Current flowing through solenoid, I=5A Magnetic permeability of free space, µ0=4π×10−7H/m We know that, magnetic field inside the solenoid can be given as B=µnI ....(i) where, µ= permeability of medium. As µ=µrµ0...(ii) From Eqs. (i) and (ii), we get ∴B=µrµ0nl =500×4π×10−7×1000×5 =100π×10−7×105 =πT