As we know that the magnetic field due to a infinite wire at a distance of d is given as
B=(4πdμ0i)
but there are two wires so that the net magnetic field is given as
B=2(4πdμ0i)
10−4=24π×(1004)4π×10−7×i
i=20A
JEE Main 2019 — Physics Electromagnetism
2019mcqmedium
As shown in the figure, two infinitely long, identical wires are bent by 90o and placed in such a way that the segments LP and QM are along the x - axis, while segments PS and QN are parallel to the y - axis. If OP=OQ=4cm, and the magnitude of the magnetic field at O is 10−4T, and the two wires carry equal currents (see figure), the magnitude of the current in each wire and the direction of the magnetic field at O will be (μ0=4π×10−7NA−2):
Official previous-year question
Held on 12 Jan 2019 · Verified 6 Jul 2026.
Options
- A
20A, perpendicular into the page
- B
20A, perpendicular out of the page
- C
40A, perpendicualr into the page
- D
40A, perpendicular out of the page
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