A solenoid of `2m` long `& 3 cm` diameter has 5 layers of winding of 500 turns per metre length in each layer `&` carries a current of `5A`. Find intensity of magnetic field at the centre of the solenoid.

Explanation

For long solenoid at the centre `B = mu_0"ni"`
`H = (B)/(mu_0) xx "ni" = (500 xx 2) 5 xx 5`
` = 2.5 xx 10^4 A/m`