Question

A circular coil of radius $5cm$ has $169$ turns carries a current of $2.6A$. The magnetic induction at a point on the axis at a distance of $12cm$ from the centre of the coil is :

• A. $2T$
• B. $4.2T$
• C. $3.14\times {10}^{-4}T$
• D. $3.14\times {10}^{-2}T$

Answer 1

The correct option is C $3.14\times {10}^{-4}T$

$B_{\left(axis\right)}=\frac{n{\mu }_0\cdot i\cdot a^2}{2(a^2+x^2{)}^{3/2}}$

$=\frac{169\times 4\pi \times {10}^{-7}\times 2\cdot 6\times 25\times {10}^{-4}}{2(25+144{)}^{3/2}\times {10}^{-6}}$

$=3\cdot 14\times {10}^{-4}T$