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Let L denote the height of capillary rise (or fall) and A the cross-sectional area of the capillary tube, with all other factors kept constant. Which quantity remains constant?
- L*A = constant
- L*sqrt(A) = constant
- L/A = constant
- L/sqrt(A) = constant
Correct answer: L*sqrt(A) = constant
Solution
From L proportional to 1/r and A = pi r² (so r proportional to sqrt(A)), we get L proportional to 1/sqrt(A). Hence L*sqrt(A) = constant.
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