Which of the following materials would have the highest resistivity value?

To determine which material has the highest resistivity value, it’s crucial to understand the concept of IACS (International Annealed Copper Standard), which quantifies the electrical conductivity of various materials relative to copper. The lower the IACS percentage, the higher the resistivity, indicating that the material is less efficient at conducting electricity.

Zirconium, with a 3.4 percent IACS rating, exhibits the highest resistivity among the listed options. This means zirconium has the greatest resistance to electrical current flow, making it a poor conductor compared to the other materials listed. In contrast, as we compare the IACS ratings of aluminum (42 percent), magnesium (37 percent), and cast steel (10.7 percent), all these materials have lower resistivity than zirconium, indicating higher conductivity.

Therefore, recognizing that resistivity inversely correlates with conductivity, the data clearly support that zirconium is the least conductive and hence has the highest resistivity value among the choices provided.