Question

A long straight wire carries a current of $35A$. The magnitude of intensity of magnetic induction at a point $20cm$ from the wire is ______ $T$.

• A. $3.5\times {10}^{-5}$
• B. $3.5\times {10}^{-3}$
• C. $3.5\times {10}^{-2}$
• D. $3.5\times {10}^{-4}$

Answer 1

Answer: (A)

$3.5\times {10}^{-5}$

$B=\frac{{\mu }_{0}i}{2\pi r}$
$B=\frac{2\times {10}^{-7}\times 35}{0.2}$
$B=3.5\times {10}^{-5}T$