Q.

Which one of the following options represents the magnetic field B→ at O due to the current flowing in the given wire segments lying on the xy plane          [2022]

1 B→=-μ0IL(32+12π4)k^  
2 B→=-μ0IL(32+122π)k^  
3 B→=-μ0IL(1+142π)k^  
4 B→=-μ0IL(1+14π)k^  

Ans.

(3)

B→=μ0I4πLsin45°(-k^)+μ0Iπ4π(L2) (-k^)+μ0I4π(L4)×π2 (-k^)

=-μ0IL[14π2+1]k^