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Four very long, current carrying wires in the same plane intersect to form a square `40.0 cm` on each side as shown in figure. Find the magnitude and direction of the current `I` so that the magnetic field at the centre of square is zero. Wires are insulated from each other. A. `4.0A` toward the bottomB. `2.0A` toward the bottomC. `2.5A` toward the bottomD. `2.6A` toward the bottom |
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Answer» Correct Answer - B (b) `BpropI`, because distance of centre for all wires is zero. `B_1=kI_1=10k ox, B_2=kI_2=8k ox` `B_3=kI_3=20k odot, B_4=kI_4` Now `B_1+B_2+B_3+B_4=0` `implies (10K+8K-20K)ox+kI_4=0` `implies kI_4=2kox` `implies I_4=2A` towards the bottom. |
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