Two very long straight wires are set parallel to each other. Each carries a current I in the same direction and the separation between them is 2r. The intensity of magnetic field at point P as shown in figure is .

Question

Accepted Answer

(3) (2μ₀ I)/(3π r). Given: two long parallel wires carrying equal currents I the same way, 2r apart; P lies on the line through both wires, a distance r beyond the nearer one. Idea: a long straight wire gives B=(μ₀ I)/(2π d) at perpendicular distance d. At P both fields are perpendicular to the page, and because P is outside the pair they point the same way, so the magnitudes add. Distances from P: d₁=r and d₂=r+2r=3r. B=(μ₀ I)/(2π r)+(μ₀ I)/(2π(3r))=(μ₀ I)/(2π r)(1+1/3). B=(μ₀ I)/(2π r)·4/3=(2μ₀ I)/(3π r).

Two very long straight wires are set parallel to each other. Each carries a current I in the same direction and the separation between them is 2r. The intensity of magnetic field at point P as shown in figure is ______.

Step-by-step solution

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