When the length of a conductor is reduced to half, its resistance becomes double. This is because resistance is directly proportional to the length of the conductor. In other words, the longer the conductor, the higher its resistance. Conversely, the shorter the conductor, the lower its resistance.

The relationship between resistance, length, and other factors is given by the following formula:

```

R = ρ * (L / A)

```

Where:

* R is resistance in ohms (Ω)

* ρ is resistivity in ohm-meters (Ω-m)

* L is length in meters (m)

* A is cross-sectional area in square meters (m²)

As you can see from the formula, resistance is directly proportional to length (L) and inversely proportional to cross-sectional area (A). This means that if you make the conductor shorter, the resistance will increase, and if you make the conductor thicker, the resistance will decrease.

In the case of reducing the length of a conductor by half, the cross-sectional area remains the same. This means that the only factor that changes is the length, which is reduced by half. Therefore, the resistance becomes double.