Read Capillaries: Balance Surface Force and Column Weight
Complete wetting means the contact angle is zero and surface tension pulls vertically upward along the full circumference of the capillary.
Chemistry questions first require the material, particles or reaction condition to be identified before a formula or rule is selected.
Start with the condition
Balance 2 π r T cos θ with rho g π r² h. Compare the predicted capillary rise with the part of the tube above the reservoir.
Build the governing relation
If the tube is shorter than the equilibrium rise, water reaches the top and the meniscus geometry changes the conclusion.
Finish with a physical check
Check the limiting case before selecting an option: remove the special feature in the diagram or make the relevant parameter very large or very small. The result should reduce to a familiar relation.
OlympIQ exam lens
- ✓State the physical condition before choosing a formula.
- ✓Keep direction, sign and constraint information explicit.
- ✓Test one limiting case before committing to an option.
Assuming the liquid must always stop at the textbook height ignores a capillary with a finite protruding length.
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