Question

Two long straight wires are set parallel to each other . Each carries a current I in the same direction and the seperation between them is 2r. What is the intensityof the magnetic field mid way between them?

Answer 1

answer :- magnetic field intensity at the mid way between them = 0.

explanation :- magnetic field due to first wire at point P is given by ,$B_1=\frac{\mu_0i}{4\pi r}$

magnetic field due to 2nd wire at point P is given by , $B_2=\frac{\mu_0i}{4\pi r}$

here you should notice that $B_1$ and $B_2$ are in just opposite directions.

so, net magnetic field = $\frac{\mu_0i}{4\pi r}-\frac{\mu_0i}{4\pi r}$ = 0

hence, net magnetic field at P = 0