Q.
A solenoid is 2m long and 3cm in diameter. It has 5 layers of winding of 1000 turns each and carries a current of 5A. What is the magnetic field at its centre ? Use the standard value of μ0.
Length of solenoid, l=2m
Total number of turns, N=5×1000=5000
Number of turns per unit length, n=lN=25000=2500m−1
Current, I=5A
Now, B=μ0nI=4π×10−7×2500×5T =1.57×10−2T