A solenoid `3*142` m long and `5*0` cm in diameter has two layers of windings of 500 turns each and carries a current of 5A. Calculate the magnetic induction at its centre along the axis.

Explanation

Data: `L=3.142 m, N=2 xx 500 = 1000, I=5A`
`mu_(0) = 4pi xx 10^(-7) T.m//A`
The magnetic induction,
`B=mu_(0)nI = mu_(0)(N/L)I = (4pi xx 10^(-7))(1000/3.142)(5)`
`=(20 xx 3.142 xx 10^(-4))/(3.142) = 2 xx 10^(-3)` T