CBSE 2026 · Region 5 · Set 1 · Q3 · 1 mark
Four long straight thin wires are held vertically at the corners A, B, C and D of a square of side 'a', kept on a table and carry equal current 'I'. The wire at A carries current in upward direction whereas the current in the remaining wires flows in downward direction. The net magnetic field at the centre of the square will have the magnitude :
Official answer
From CBSE’s own marking scheme for this paper.
(C)
$\displaystyle \frac{\mu_{0} \mathrm{I} \sqrt{2}}{\pi \mathrm{a}}$ and directed along OB
Moving Charges and MagnetismAmpere’s Circuital LawApplymcqmedium
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CBSE Class 12 Physics past-paper question from the 2026board exam, with the answer as CBSE’s own marking scheme gives it. Where our answers come from.