Two identical current carrying coils with same centre are placed with their planes perpendicular to each…

Two identical current carrying coils with same centre are placed with their planes perpendicular to each other. If current $I=\sqrt{2} \mathrm{~A}$ and radius of the coil is $\mathrm{R}=1 \mathrm{~m}$, then magnetic field at centre is equal to ( $\mu_0=$ permeability of free space)
  1. $\mu_0$
  2. $\frac{\mu_0}{2}$
  3. $2 \mu_0$
  4. $\sqrt{2} \mu_0$

Solution

$\begin{aligned} i & =\sqrt{2} A \\ B_{n e t} & =\sqrt{B_1^2+B_2^2} \\ & =\sqrt{\left(\frac{\mu_0 i}{2 R}\right)^2+\left(\frac{\mu_0 i}{2 R}\right)^2}=\sqrt{2\left(\frac{\mu_0 \mathrm{i}}{2 R}\right)^2} \\ & =\sqrt{2 \frac{\mu_0^2 \mathrm{i}^2}{4 \mathrm{R}^2}}=\sqrt{\frac{1}{2}\left(\frac{\mu_0 \mathrm{i}}{R}\right)^2} \\ & =\frac{1}{\sqrt{2}} \frac{\mu_0 \mathrm{i}}{\mathrm{R}}=\frac{1}{\sqrt{2}} \times \frac{\mu_0 \sqrt{2}}{1}=\mu_0\end{aligned}$

Asked in: MHT CET 2024 (02 May Shift 1)

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