Question

A wire of length $44cm$ is bent into a circle and a current of $9.8A$ is passed through it. The intensity of magnetic induction at the centre of the circle is

• A. $8.8\times {10}^{-6}T$
• B. $8.8\times {10}^{-5}T$
• C. $8.4\times {10}^{-6}T$
• D. $61.5\times {10}^{-5}T$

Answer 1

The correct option is B $8.8\times {10}^{-5}T$

wire is bent into a circle.

so $l=2\pi R$

$R=\frac{l}{2\pi }$

$=\frac{44}{2\pi }cm$

$=\frac{22}{\pi }cm$

$B=\frac{{\mu }_{0}i}{2R}$

$=\frac{4\pi \times {10}^{-7}\times 9\cdot 8}{2\times \frac{22}{\pi }\times {10}^{-2}}$

$=8\cdot 8\times {10}^{-5}T$