Magnetic Effects & Magnetism

JEE Main level, numerical answer, medium

5 of 276

Question 5 of 276

Two identical circular wires of radius 20cm20cm and carrying current 2A\sqrt{2}A are placed in perpendicular planes as shown in figure. The net magnetic field at the centre of the circular wires is________\times {10}^{-8}T.

(Take
π=3.14\pi =3.14)

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Answer: 628

The formula to calculate the magnetic field (B)\left(B\right) at the centre of a current carrying circular loop is given by
B=μ0i2R...(1)B=\dfrac{{\mu }_{0}i}{2R}...(1)
where,
μ0{\mu }_{0} is the permeability of free space, ii is the current and RR is the radius of the loop.
BV,BH{B}_{V},{B}_{H} are the magnetic field due to the vertical and the horizontal loop, which by magnitude are equal.
The resultant magnetic field
(Bnet)\left({B}_{net}\right) at the centre is, then, given by
Bnet=B2+B2=2B=2×4π×10−7×22×0.2{B}_{\text{net}}=\sqrt{{B}^{2}+{B}^{2}}=\sqrt{2}B =\dfrac{\sqrt{2}\times 4\pi \times {10}^{-7}\times \sqrt{2}}{2\times 0.2}
=628×10−8T=628\times {10}^{-8}T

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