Due to currents in infinite long wire at `A` and `B`, magnetic field is maximum at `M` and at `P`, magnetic field as shown. Then

Options

A. Current is `A` and `B` is equal in magnitude and outside the plane of paper
B. Current is `A` and `B` is equal in magnitude and inside the plane of paper
C. Current in `A` and `B` is equal in magnitude, in `A` outside, in `B` inside
D. Current in `A` and `B` is equal in magnitude, in `A` inside, in `B` inside

Answer

C

Explanation

Since magnetic field at `M` is maximum, for this current in `A` and `B` should be in opposite be in opposite direction. Let current in wire `A` is in `+z` direction and in wire `B` is in `B` is in `z` direction.

At `P:`
Due to `A, B_(A)=(mu_(0)i_(1))/(2pi(d^(2)+x^(2))^(1//2))`
Due to `B, B_(B)=(mu_(0)i_(2))/(2pi(d^(2)+x^(2))^(1//2))`
Since magnetic field at `P` is along `+x` axis i.e.
`B_(A)=B_(B) implies i_(1)=i_(2)`