Two parallel long wires A and B carry currents I1 and I2 . (I2 < I1 ) when I1 and I2 are in the same direction the mag. field at a point mid way between the wires is 10 µT. If I2 is reversed, the field becomes `30 muT` . The ratio `I_1/ I_2` is

Question

Two parallel long wires A and B carry currents I₁ and I₂ . (I₂ < I₁ ) when I₁ and I₂ are in the same direction the mag. field at a point mid way between the wires is 10 µT. If I₂ is reversed, the field becomes `30 muT` . The ratio `I_1/ I_2` is ........................

Options:
(a) 1 (b) 2 (c) 3 (d) 4