Two long wires are placed parallel to each other. The current carried by these wires is, `i_(1)" and " i_(2)`, respectively. Assume `i_(1) gt i_(2)`. When current is flowing in the same direction then magnetic field midway between the two wires is `20 mu T`. If direction of `i_(2)`, is reversed then magnetic field at the same point becomes `60 mu T`. What should be the ratio of currents?

Explanation

To solve the problem, we will use the formula for the magnetic field due to a long straight current-carrying wire and apply it to the two scenarios described in the question.

### Step-by-step Solution:

1. **Understanding the Magnetic Field Between Two Wires:**
When two parallel wires carry currents in the same direction, the magnetic field at a point midway between them is given by:
\[
B_1 = \frac{\mu_0 (I_1 - I_2)}{2 \pi D}
...