For capillary determination of water surface tension, diameter D = 1.25×10⁻² m and rise h = 1.45×10⁻² m are measured. Using g = 9.80 m s⁻² and T = (r h g/2)×10³ N m⁻¹, find the possible percentage error in T.
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Question

For capillary determination of water surface tension, diameter D = 1.25×10⁻² m and rise h = 1.45×10⁻² m are measured. Using g = 9.80 m s⁻² and T = (r h g/2)×10³ N m⁻¹, find the possible percentage error in T.

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G1 Physics · Accepted Answer

For T=ρghr/2, percentage error = percentage error in h + percentage error in r (g and ρ taken exact). Using the stated measurement precisions gives about 1.5%. Correct answer: D.