Question

Determine the amount of current flowing through the solenoid having $5000\text{turns}$ per unit length, if the magnetic field at the edge of the solenoid is $2.2\pi \times {10}^{-5}\text{T}$.

• A. $0.02\text{A}$
• B. $0.2\text{A}$
• C. $0.002\text{A}$
• D. $2\text{A}$

Answer 1

The correct option is A $0.02\text{A}$

Given:
$n=5000;B=2.2\pi \times {10}^{-5}\text{T}$

We know that, magnetic field at the edge of the solenoid is given by

$B=\frac{{\mu }_{0}ni}{2}$

$\therefore i=\frac{2B}{{\mu }_{0}n}=\frac{2\times 2.2\pi \times {10}^{-5}}{4\pi \times {10}^{-7}\times 5000}$

$i=\frac{1.1\times {10}^{-5}}{5\times {10}^{-4}}=\frac{1.1\times {10}^{-1}}{5}$

$\therefore i=\frac{0.11}{5}=0.02\text{A}$

Hence, option $\left(a\right)$ is correct.