Question

A circular coil has a radius of $16cm$ and contains $50$ turns. If a current of $2A$ is passed through the coil, the magnetic flux density at its centre is

• A. $3.9\times {10}^{-4}T$
• B. $2\times {10}^{-4}T$
• C. $3.2\times {10}^{-4}T$
• D. $2.8\times {10}^{-4}T$

Answer 1

The correct option is A $3.9\times {10}^{-4}T$

$B=\frac{n{\mu }_{0}i}{2r}$
$=\frac{50\times 4\times \pi \times {10}^{-7}\times 2}{2\times 16\times {10}^{-2}}$
$=3.9\times {10}^{-4}T$