The earth’s magnetic field at a given point is 0.5 x 10^–5 Wb m^–2. This field is to be annulled by magnetic induction at the centre of a circular conducting loop of radius 5.0 cm. The current reqired to be flown in the loop is nearly

0.4A

The magnetic field due to a circular loop at the centre is given by $B = \frac{\mu_0 I}{2r} \Rightarrow I = \frac{2Br}{\mu_0}$

B = 0.5 x 10^–5 Wb m^–2

r = 5cm 

$\Rightarrow I = 0.4A$