# A solenoid of 2 m long & 3 cm diameter has 5 layer of windings of 500 turns per metre length in each layer & carries a current of 5 A…

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

Sol: For long solenoid at the centre , B = μ0 n i

$\large H = \frac{B}{\mu_0} = n i$

= (500 × 2)5 × 5

= 2.5 × 104 A/m.