Question

A current of $0.1\text{A}$ circulates around a coil of $100$ turns and having a radius equal to $5\text{cm}$. The magnetic field set up at the centre of the coil is
(${\mu }_0=4\pi \times {10}^{-7}\text{weber/ampere-metre}$)

• A. $4\pi \times {10}^{-5}\text{tesla}$
• B. $8\pi \times {10}^{-5}\text{tesla}$
• C. $4\times {10}^{-5}\text{tesla}$
• D. $2\times {10}^{-5}\text{tesla}$

Answer 1

The correct option is A $4\pi \times {10}^{-5}\text{tesla}$

$B=\frac{{\mu }_{0}Ni}{2r}=\frac{4\pi \times {10}^{-7}\times 100\times 0.1}{2\times 5\times {10}^{-2}}$
$=4\pi \times {10}^{-5}\text{Tesla}$