The magnitude of magnetic field at O due to a current carrying loop as shown in the figure is, where O is the centre of two circular portions with radii 1 ~cm and 2 ~cm respectively is (Take, the value of current I= 1.2 A )

Step-by-step solution

Wire lengths a b and c d does not produces any field at O as this point lies an axis of wires. Arc b c produces an inward magnetic field given by B₁= ₀ I 2 R₁ 360^ aligned & = 4 10⁻⁷ 2 2 10⁻² 1.2 30 360 & = 10⁻⁷ 10⁻² 10 =10⁻⁶ ~T & =10^3 10⁻⁹ ~T =1000 nT aligned Arc ad produces an outward magnetic field given by B₂= ₀ I 2 R₂ 360^ = 4 10⁻⁷ 1.2 30 2 1 10⁻² 360 aligned & = 2 10⁻⁷ 10⁻² 10 =2 10⁻⁶ & =2 10^3 10⁻⁹ ~T =2000 nT aligned Net field at centre aligned & =B₂ -B₁ =2000-1000 & =1000 nT =10^3 10⁻⁹ ~T & =10⁻⁶ ~T =1 T