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Resistivity Formula:
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Conductivity measures water's ability to conduct electric current, while resistivity measures its opposition to electric current flow. They are inversely related and fundamental parameters in water quality assessment.
The calculator uses the fundamental relationship:
Where:
Explanation: This inverse relationship means that as conductivity increases (more ions in water), resistivity decreases, and vice versa.
Details: Resistivity is crucial for assessing water purity, especially in industrial applications, pharmaceutical manufacturing, semiconductor production, and laboratory water systems where high-purity water is essential.
Tips: Enter conductivity value in S/cm (siemens per centimeter). The value must be greater than 0. For ultra-pure water measurements, scientific notation may be appropriate for very low conductivity values.
Q1: What is the typical resistivity of pure water?
A: Ultra-pure water at 25°C has resistivity of approximately 18.2 MΩ·cm (megaohm centimeters).
Q2: How does temperature affect conductivity and resistivity?
A: Conductivity increases with temperature (approximately 2% per °C), so measurements are often temperature-compensated to 25°C.
Q3: What units are commonly used for water conductivity?
A: Microsiemens per cm (μS/cm) is common for drinking water, while pure water uses μS/cm or even nS/cm (nanosiemens per cm).
Q4: Why is high resistivity important in certain industries?
A: High resistivity indicates low ion content, which is critical for semiconductor manufacturing, pharmaceutical production, and power generation to prevent contamination and equipment damage.
Q5: Can this calculator handle different conductivity units?
A: This calculator requires input in S/cm. For other units like μS/cm, divide by 1,000,000 first (1 μS/cm = 0.000001 S/cm).