A solenoid has length 0.4 cm, radius 1 cm and 400 turns of wire. If a current of 5 A is passed through this solenoid, what is the magnetic field inside the solenoid?

The magnetic field inside the solenoid is given by B =μ0ni0(n = number of turns per unit length, i = current in coil μ0=4⋅π×10−7Tm⁡/Awhere, n=NLr⇒n=4000.4×10−2×1×10−2⇒n=1000B=4×3.14×1000×5×10−7=63800×10−7=6.28×10−3T