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Physics · PYQ NEET UG 2017
हिन्दीAn arrangement of three parallel straight wires placed perpendicular to plane of paper carrying same current '\( I \)' along the same direction is shown in figure. Magnitude of force per unit length on the middle wire '\( B \)' is given by
Correct answer · Option 4
\( \frac{\mu_0 I^2}{\sqrt{2}\pi d} \)
Explanation
Force per unit length between parallel wires is \( F/l = \frac{\mu_0 I_1 I_2}{2\pi r} \). Forces due to A and C act at 90 degrees to each other, giving a resultant of \( \sqrt{2} \frac{\mu_0 I^2}{2\pi d} = \frac{\mu_0 I^2}{\sqrt{2}\pi d} \).
