Which conductor type has a high impedance for electricity but is still considered good?

The conductor type identified as having a high impedance for electricity while still being considered good is aluminum. Aluminum is lightweight and generally less expensive than other conductor materials, making it a popular choice for overhead power lines and large electrical applications.

Despite having a higher resistivity (or impedance) compared to materials like copper or gold, aluminum is still regarded as a good conductor due to its favorable balance between conductivity, weight, and cost. It is widely used in various electrical installations and systems, particularly where the weight of the conductor is a significant concern.

Copper, while an excellent conductor with lower impedance, is typically more expensive and heavier, which makes aluminum a more practical choice in specific situations. Steel, although it has some conductive properties, is primarily used for structural purposes rather than as a conductor of electricity. Gold, while it has excellent conductivity, is not commonly used for electrical wiring due to its high cost.

In summary, aluminum's favorable attributes in terms of cost-effectiveness, weight, and adequate conductivity make it a suitable choice despite its higher impedance compared to other metals.