Magnetic effect

Ans given is 4

@SiddharthaGhosh
Hope you understand it.

@prithvirajbhonsle wire BC current direction is reverse and Bab will be into the plane not out of the plane and for other wires it out of the plane .
And I didn't understand why R × I1 =2R ×I2
I mean why 2R as two similar paths are there thro8gh which current is flowing

@SiddharthaGhosh
I’m sorry. I assumed a different situation.

Anyone pls help

@SiddharthaGhosh Magnetic field due to the wire(outside the triangle) is 0 at O....hence for any loop(current flowing from one end to other end)......magnetic field at geometric centre is always zero
You can also calculate mathematically.
This happens due to unequal distribution of currents in the triangle.

@SiddharthaGhosh assume currents as I1,I2,I3 on the inside triangle in the given directions as shown in fig.
Apply KCL and KVL You will get values of I1,I2,I3 in terms of I . Now write mag. Fields
It should come as zero

@SiddharthaGhosh current direction reverse is not possible .
It's a misprint in question
It violates kirchoff's current law.
Solution provided by @prithvirajbhonsle is correct .

@Kirito still then the directions were wrong(Direction of B)
And why 2R × I2 i mean why 2R