A **mercury barometer** measures:
- Density of mercury
- Atmospheric pressure
- Specific gravity of liquids
- Viscosity
Show answer and solution
Correct answer: B. Atmospheric pressure
**Torricelli's barometer:** inverted glass tube of mercury in a dish
atmospheric pressure $p_a = h\rho g$ where $h$ is the mercury column height (typically 76 cm at sea level).
Above the mercury column is Torricelli vacuum.