$PQ$ and $RS$ are long parallel conductors separated by certain distance. $M$ is the mid-point between them (see the figure). The net magnetic field at $M$ is $B$. Now, the current 2 A is switched off. The field at $M$ now becomes

Question

Dr. Abubacker · Accepted Answer

(b) Magnetic field at mid-point $M$ in first case is $B = B_{PQ} - B_{RS}$
$(	herefore B_{PQ}\ and\ B_{RS}\ are\ in\ opposite\ directions)$
$= \frac{4{\ \mu}_{0}}{4\pi d} - \frac{2\ \mu_{0}}{4\pi d} = \frac{2{\ \mu}_{0}}{4\pi d}$
When the current 2 A is switched off, the net magnetic field at $M$ is due to current 1 A
$B^{'} = \frac{\mu_{0} 	imes 2 	imes 1}{4\pi d} = B$

Q. $PQ$ and $RS$ are long parallel conductors separated by certain distance. $M$ is the mid-point between them (see the figure). The net magnetic field at $M$ is $B$. Now, the current 2 A is switched off. The field at $M$ now becomes

Explanation

Reviewed by Dr. Abubacker

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