Two concentric co-planar circular Loops of radii `r_1` and `r_2` carry currents of respectively I
1 and I
2 in opposite directions. The magnetic induction at the centre of the Loops is half that due to I
1 alone at the centre. If `r_2 = 2r_1` the value of `I_2/ I_1` is
Options:
(a) 2
(b) `1/2`
(c) `1/4`
(d) 1