Surface Tension (S = F/(2l))
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S = F/(2l)
What each symbol means
| Symbol | What it stands for |
|---|---|
| F | Force required to stretch the film (N) |
| S | Surface tension (N/m or J/m²) |
| l | Length of the movable edge (m) |
When to use this
Surface tension acts in the plane of the liquid surface. Equal to surface energy per unit area (J/m²) and force per unit length (N/m). Factor 2 arises because a film has two surfaces. Decreases with increasing temperature. S for water ≈ 0.073 N/m at 20°C, mercury ≈ 0.436 N/m.