question_answer

Two long parallel straight conductors carry current \[{{\text{i}}_{\text{1}}}\], and \[{{\text{i}}_{2}}\]\[\text{(}{{\text{i}}_{1}}>{{\text{i}}_{\text{2}}}).\]When the currents are in the same direction, the magnetic field at a point midway between the wires is \[20\mu T\]. If the direction of \[{{\text{i}}_{\text{2}}}\]is reversed, the field becomes \[50\mu T\]. The ratio of the currents \[{{\text{i}}_{1}}\text{/}{{\text{i}}_{\text{2}}}\]is:

A)  5/2                                       

B)  7/3

C)  4/3                                       

D)  5/3