Question

A closely wound, solenoid $80\text{cm}$ long has $5$ layers of winding of $400$ turns each. The diameter of the solenoid is $1.8\text{cm}$. If the current carried is $8.0\text{A}$. Estimate the magnetic field Inside the solenoid

• A. $2\pi \times {10}^{-3}\text{T}$
• B. $16\pi \times {10}^{-3}\text{T}$
• C. $8\pi \times {10}^{-3}\text{T}$
• D. $4\pi \times {10}^{-3}\text{T}$

Answer 1

The correct option is C $8\pi \times {10}^{-3}\text{T}$

Given that,
$l=80\text{cm};i=8\text{A};N=2000\text{turns}$

Number density , $n=\frac{2000}{0.8}=2500\frac{\text{turns}}{\text{cm}}$

We know that,

$B={\mu }_{0}ni=4\pi \times {10}^{-7}\times 250\times 8=8\pi \times {10}^{-3}\text{T}$

Hence, option (c) is the correct answer.