$PQ$ 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 $4 \mathrm{A}$ is switched off. The field at $M$ now becomes

Equal currents $\mathrm{I}$ and $\mathrm{I}$ are flowing through two infinitely-long parallel wires. What will be the magnetic field at a point mid-way between them, when the currents are in same direction,

Equal currents $\mathrm{I}$ and $\mathrm{I}$ are flowing through two infinitely-long parallel wires. What will be the magnetic field at a point mid-way between them, when the currents are in opposite directions ?

Two infinitely long insulated wires are kept perpendicular to each other. They carry currents $I_{\mathit{1}}\mathit{ }\mathit{=}\mathit{ }\mathit{2}A$ and ${\mathrm{I}}_2 = 1.5\mathrm{A}$ .

(i) Find the magnitude and direction of the magnetic field at $\mathrm{p}$.