As shown in the figure, a current of 2A flowing in an equilateral triangle of side 4√3 cm . The magnetic field at the centroid O of the triangle is :…
JEE Main 2023 — Physics Electromagnetism
2023mcqhard
As shown in the figure, a current of 2A flowing in an equilateral triangle of side 43cm . The magnetic field at the centroid O of the triangle is :
(Neglect the effect of earth’s magnetic field)
Official previous-year question
Held on 30 Jan 2023 · Verified 6 Jul 2026.
Options
A
43×10−4T
B
43×10−5T
C
3×10−4T
D
33×10−5T
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Solution
Perpendicular distance of centroid from any of the sides will be, dtan60∘=23
⇒d=2cm
Each side will subtend an angle of 120∘ at the centre. Also magnetic field due to all sides will be out of plane of paper, hence total magnetic field can be written as
B=3×4πdμ0i[sin60∘+sin60∘]
=3×2×10−210−7×2×3
=33×10−5T
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