In this blog, we will review the concept of resistance, resistivity and steps to calculate the minimum cross-sectional area and diameter of any desired conductor.

## What is Resistance?

The property of a device or a circuit that opposes the movement of current through it. Resistance is measured in Ohms (Ω). The resistance of any material with a uniform cross-sectional area is determined by the following four factors:

- The kind of material
- The length
- The cross-sectional area
- The temperature

## What is Resistivity?

Resistivity is the measure of how much a given size of specific material resists the current flow. While materials resist electrical current flow, some are better at conducting it than others. Resistivity is used to compare the inherent resistance characteristics of different materials. Materials that easily conduct current are referred to as conductors. Conductors have a low resistivity. While the materials that do not easily conduct current are referred to as insulators. Insulators have a high resistivity. The resistivity of a material plays an important role in choosing the materials used for electric wire.

Now that we understand the concept of resistance and resistivity clearly, let’s review the general relationship of basic conductor resistance, which suggests that the resistance of a given conductor is equal to the material resistivity times the ratio of its length to its cross-sectional area. This can help us to calculate the minimum cross-sectional area and diameter of any desired conductor.

Example: What is the minimum cross-sectional area and diameter of conductor for a 750-meter-long copper wire having a maximum resistance of 0.2 ohms?