Question

Two parallel, long wires carry currents t, and $i_1$ with $i_1>i_2$. When the currents are in the same direction, the magnetic field at a point midway between the wires is $10pT$. If the direction of $i_2$ is reversed, the field becomes $30pT$. The ratio $\frac{i_1}{i_2}$ is

• A. 4
• B. 3
• C. 2
• D. 1

Answer 1

Answer: (C)