Moving Charges And Magnetism

Two parallel conductors carry current in opposite directions as shown in the figure. One conductor carries a current of \(20 \mathrm{~A}\). Point \(C\) is a distance \(d / 2\) to the right of a 20 A current. If \(d=18 \mathrm{~cm}\) and \(i\) is adjusted so that the magnetic field at \(C\) is zero, the value of the current \(i\) is