In the given figure, net magnetic field at O will be

Magnetic field at O due toPart (1):B1=0Part(2):B2=μ04π⋅πi(a/2)⊗ ( along −Z-axis) Part(3):B3=μ04π⋅i(a/2)(↓) ( along −Y-axis)  Part (4): B4=μ04π⋅πi(3a/2)⊙  (along +Z-axis)  Part (5):B5=μ04π⋅i(3a/2)(↓) ( along −Y-axis) B2−B4=μ04π⋅πia2−23=μ0i3a⊗B3+B5=μ04π⋅ia2+23=8μ0i12πa(↓) ( along −Y-axis )Hence, net magnetic fieldBnet=B2−B42+B3+B52=μ0i3πaπ2+4