The magnetic field at the centre of a circular coil of radius r, due to current I flowing through it, is B. The magnetic field at a point along the axis at a distance ${r \over 2}$ from the centre is :
Solution
<p>$B = {{{\mu _0}I} \over {2r}}$</p>
<p>${B_a} = {{{\mu _0}I{r^2}} \over {2\left( {{r^2} + {{{r^2}} \over 4}} \right)}}$</p>
<p>$\Rightarrow {{{B_a}} \over B} = {\left( {{2 \over {\sqrt 5 }}} \right)^3}$</p>
<p>$\Rightarrow {B_a} = {\left( {{2 \over {\sqrt 5 }}} \right)^3}B$</p>
About this question
Subject: Physics · Chapter: Magnetic Effects of Current · Topic: Biot-Savart Law
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