How long is the K-4 electrode?

The K-4 electrode is specifically designed to measure groundwater levels and is typically 150 feet in length. This standard length allows for effective measurement in various geological conditions encountered during water level monitoring. Understanding the dimensions of the K-4 electrode is critical for anyone involved in environmental monitoring, hydrology, or related fields, as it ensures the correct implementation of monitoring systems.

The other options do not match the standard specifications for the K-4 electrode, and thus they are not considered correct.