Answer:
The magnitude of magnetic field decreases in comparison to previous case.
Explanation:
Let current flowing in two conductors are [tex]I_1[/tex] and [tex]I_2[/tex]
Magnetic field in wire,[tex]B=\frac{\mu_0 I}{2\pi r}[/tex]
Magnetic field due to current I1
[tex]B_1=\frac{\mu_0 I_1}{2\pi r}[/tex]
Magnetic field due to current I2
[tex]B_2=\frac{\mu_0 I}{2\pi r}[/tex]
When two parallel conductors are carrying currents in the same direction then the magnetic field will be added.
[tex]B=B_1+B_2=40\mu T[/tex]
When the direction of one of the current is reversed then the magnitude of the magnetic field midway between them
[tex]B=B_1-B_2=\frac{\mu_0I_1}{2\pi r}-\frac{\mu_0 I_2}{2\pi r}[/tex]
[tex]B=\frac{\mu_0(I_1-I_2)}{2\pi r}[/tex]
Hence, the magnitude of magnetic field decreases in comparison to previous case.