Question

The magnetic intensity H at the centre of a long solenoid carrying a current of 2.0 A, is found to be 1500 A m⁻¹. Find the number of turns per centimetre of the solenoid.

Answer 1

Here,
Current in the solenoid, I = 2 A
Magnetic intensity at the centre of long solenoid, H = 1500 Am⁻¹
Magnetic field produced by a solenoid$\left(B\right)$ is given by
B = µ₀ni ...(1)
Here, n = number of turns per unit length
i = electric current through the solenoid
Also, the relation between magnetic field strength$\left(B\right)$ and magnetic intensity$\left(H\right)$ is given by
H = $\frac{B}{{\mathrm{\mu }}_0}$ ...(2)
From equations (1) and (2), we get:
H = ni
⇒ 1500 A/m = n × 2
⇒ n = 750 turns/meter
⇒ n = 7.5 turns/cm