Why is the Earth considered a poor conductor?

The Earth is considered a poor conductor primarily due to its high impedance. Impedance in electrical terms refers to the opposition that a circuit presents to a current when a voltage is applied. In the case of the Earth, it contains various materials, such as soil, rocks, and moisture, which contribute to its overall impedance.

Though the Earth can conduct electricity to some extent, the materials that make up the Earth's surface generally have relatively high resistive properties. These properties hinder the flow of electrical current, making it less effective as a conductive medium compared to metals like copper or aluminum.

While low resistance would indicate a good conductor, the Earth’s characteristics lead to higher resistance values, reinforcing the notion that it does not facilitate easy current flow. Understanding impedance helps in assessing how effectively electrical systems can ground themselves and how much loss might occur in the process. Therefore, high impedance provides a more accurate description of the electrical behavior of Earth as a conductor.