Easy MCQ +4 / -1 PYQ · JEE Mains 2022

The magnetic field at the center of current carrying circular loop is $B_{1}$. The magnetic field at a distance of $\sqrt{3}$ times radius of the given circular loop from the center on its axis is $B_{2}$. The value of $B_{1} / B_{2}$ will be

  1. A 9 : 4
  2. B 12 : $\sqrt5$
  3. C 8 : 1 Correct answer
  4. D 5 : $\sqrt3$

Solution

<p>${B_1} = {{{\mu _0}i} \over {2R}}$</p> <p>${B_2} = {{{\mu _0}i{R^2}} \over {2{{({R^2} + {x^2})}^{{3 \over 2}}}}}$</p> <p>$$ \Rightarrow {{{B_1}} \over {{B_2}}} = {1 \over {{R^3}}}{({R^2} + {x^2})^{{3 \over 2}}}$$</p> <p>$= {1 \over {{R^3}}}(8{R^3})$</p> <p>$= 8$</p>

About this question

Subject: Physics · Chapter: Magnetic Effects of Current · Topic: Biot-Savart Law

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