WAEC Physics 2018 Objective — Question 27
Question 27 of 50 from the West African Examinations Council (WAEC) Physics 2018 Objective paper, with the correct answer and a full explanation.
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A simple barometer is constructed using a liquid Q, of density 16.2g/cm³. Calculate the least length of the tube to be used to measure a pressure of 1.5 atmospheres. (Density of mercury = 13.6g/cm³, 1 atmosphere = 76.0cm of mercury)
- A. 1358mm
- B. 957mmCorrect
- C. 760mm
- D. 638mm
Explanation
Equivalent mercury height = 1.5×76 = 114cm. Using ρ_Hg h_Hg = ρ_Q h_Q: h_Q = (13.6×114)/16.2 ≈ 95.7cm = 957mm.
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