# A solenoid of 1000 turns

Question:

A solenoid of 1000 turns per metre has a core with relative permeability 500 . Insulated windings of the solenoid carry an electric current of $5 \mathrm{~A}$. The magnetic flux density produced by the solenoid is :

(permeability of free space $=4 \pi \times 10^{-7} \mathrm{H} / \mathrm{m}$ )

1. $\pi \mathrm{T}$

2. $2 \times 10^{-3} \pi \mathrm{T}$

3. $\frac{\pi}{5} \mathrm{~T}$

4. $10^{-4} \pi \mathrm{T}$

Correct Option: 1

Solution:

$\mathrm{B}=\mu \mathrm{nI}=\mu_{0} \mu_{\mathrm{r}} \mathrm{nI}$

$\mathrm{B}=4 \pi \times 10^{-7} \times 500 \times 1000 \times 5$

$\mathrm{~B}=\pi$ Tesla