Question

If the magnetic field a perpendicular distance r to the left of a current-carrying wire is 10 T, what will the net magnetic field at the same point be if a second wire with a current twice as strong and flowing in the opposite direction is placed a distance r to the right of the original wire?

Answer 1

Answer:

30 T

Explanation:

The magnetic field due to first wire at point A is $B_1=\frac{\mu _0i}{2\pi r}$

Magnetic field due to second wire at point A  is  $B_2=\frac{\mu _02i}{2\pi r}$

As the current flows in opposite direction in both the wire so net magnetic magnetic field at point A is $B=B_1+B_2=\frac{\mu _0i}{2\pi r}+\frac{\mu _02i}{2\pi r}=\frac{\mu _03i}{2\pi r}$

So net magnetic field $B=3B_1=3\times 10=30T$  as $B_1$  is given as 10 T  in question