A barometer tube of radius 1 mm contains mercury (surface tension 0.45 N / m and contact angle 143° ). If atmospheric pressure is 75 cm of mercury column, what is height of mercury in the tube ρ Hg =13.5 gm / cc. [Take g =10 ms -2 ]

Question

A barometer tube of radius 1 mm contains mercury (surface tension 0.45 N / m and contact angle 143° ). If atmospheric pressure is 75 cm of mercury column, what is height of mercury in the tube ρ Hg =13.5 gm / cc. [Take g =10 ms -2 ] (A) 75 cm (B) 73.2 cm (C) 75.4 cm (D) 74.6 cm

Tardigrade Admin · Accepted Answer

<img class="img-fluid question-image" alt="image" src="https://cdn.tardigrade.in/img/question/physics/faec25d85fc88352e97860747b19e892-.png" /> h=75-(25 cos 53°/r ρ g) =0.75-(2 × 0.45 × (3/5)/10-3 × 13.5 × 103 × 100) =0.75-0.004 =0.746 m

Q. A barometer tube of radius $1 mm$ contains mercury (surface tension $0.45 N / m$ and contact angle $14 3^{\circ}$ ). If atmospheric pressure is $75 c m$ of mercury column, what is height of mercury in the tube $ρ_{H g} = 13.5 g m / cc$ .
[Take $g = 10 m s^{- 2}$ ]

75 cm

73.2 cm

75.4 cm

74.6 cm

$h = 75 - \frac{25 c o s 5 3 ^{\circ}}{r ρ g}$
$= 0.75 - \frac{2 \times 0.45 \times \frac{3}{5}}{1 0 ^{- 3} \times 13.5 \times 1 0 ^{3} \times 100}$
$= 0.75 - 0.004$
$= 0.746 m$

Q. A barometer tube of radius 1mm contains mercury (surface tension 0.45N/m and contact angle 143∘ ). If atmospheric pressure is 75cm of mercury column, what is height of mercury in the tube ρHg​=13.5gm/cc. [Take g=10ms−2 ]