Formula To Calculate Surface Tension

Surface Tension Formula:

\[ \gamma = \frac{\rho \cdot g \cdot r \cdot h}{2} \]

Surface Tension (γ):

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1. What is Surface Tension?

Surface tension is the elastic tendency of a fluid surface which makes it acquire the least surface area possible. It is caused by the cohesive forces between liquid molecules at the fluid's surface.

2. How Does the Formula Work?

The calculator uses the capillary rise formula:

\[ \gamma = \frac{\rho \cdot g \cdot r \cdot h}{2} \]

Where:

\( \gamma \) — Surface tension (N/m)
\( \rho \) — Density of the liquid (kg/m³)
\( g \) — Gravitational acceleration (9.8 m/s²)
\( r \) — Radius of the capillary tube (m)
\( h \) — Height of liquid rise in the capillary (m)

Explanation: This formula calculates surface tension based on the capillary rise method, where a liquid rises in a narrow tube due to surface tension forces.

3. Importance of Surface Tension Calculation

Details: Surface tension measurement is crucial in various fields including physics, chemistry, biology, and engineering. It helps understand fluid behavior, design microfluidic devices, study biological membranes, and develop coatings and detergents.

4. Using the Calculator

Tips: Enter density in kg/m³, radius in meters, and height in meters. All values must be positive numbers. The calculator uses standard gravity (9.8 m/s²) in the calculation.

5. Frequently Asked Questions (FAQ)

Q1: What is the physical significance of surface tension?
A: Surface tension determines how liquids interact with surfaces and other liquids, affecting phenomena like capillary action, droplet formation, and wetting behavior.

Q2: Why is the capillary rise method used?
A: The capillary rise method provides a simple and accurate way to measure surface tension by observing the height a liquid rises in a narrow tube due to capillary action.

Q3: What factors affect surface tension measurements?
A: Temperature, impurities, and the nature of the liquid and solid surfaces can significantly affect surface tension measurements.

Q4: What are typical surface tension values?
A: Water at 20°C has a surface tension of about 0.072 N/m, while mercury has about 0.465 N/m. Organic liquids typically have lower values.

Q5: Can this formula be used for all liquids?
A: This formula works well for liquids that wet the capillary tube completely. For non-wetting liquids or complex fluids, additional considerations may be needed.