Q 12-04-210JEE MainJEE Main 2019 (8 Apr, Shift 2)Easy
Two very long, straight, and insulated wires are kept at $90^\circ$ angle from each other in $xy$-plane as shown in figure. These wires carry currents of equal magnitude $I$, whose directions are shown in the figure. The net magnetic field at point P will be
Answer: (D) Zero
P is at distance $d$ from each wire.
Vertical wire (current along $+\hat y$), P on its right: field $\dfrac{\mu_0I}{2\pi d}$ along $\hat y\times\hat x = -\hat z$.
Horizontal wire (current along $+\hat x$), P above it: field $\dfrac{\mu_0I}{2\pi d}$ along $\hat x\times\hat y = +\hat z$.
The two fields are equal and opposite, so the net field at P is zero.
Solution by Sreeraj P, M.Sc Physics