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Build Your Own Barometer

Explore the fascinating physics behind atmospheric pressure measurement through interactive barometer simulations. Learn how mercury barometers work, understand hydrostatic pressure, and discover the relationship between atmospheric pressure and fluid column height.

Core Barometer Principle
Understand the fundamental principle: P_atm = ρgh and why mercury settles at a specific height
Fluid Type
Altitude
Barometer Simulation

Click 'Invert Tube' to start the experiment

Real-time Data
Fluid:Mercury
Density (ρ):13600 kg/m³
Pressure:101325 Pa
Column Height:— cm
Theoretical:75.9 cm
Container Level:60.0 cm
Pressure Formula
P = ρgh
P: Pressure (101325 Pa)
ρ: Fluid density (13600 kg/m³)
g: Gravity (9.81 m/s²)
h: Column height (100.0 cm)
Animation Progress
1. Initial Setup
2. Moving Tube
3. Inverting Tube
4. Mercury Flowing
5. Equilibrium Reached
Understanding the Physics

The Barometer Principle

A barometer measures atmospheric pressure using the principle of hydrostatic equilibrium. When a tube filled with mercury is inverted into a bowl of mercury, the atmospheric pressure pushes down on the mercury in the bowl, supporting a column of mercury in the tube.

Key Equation: P_atm = ρgh

  • P_atm: Atmospheric pressure
  • ρ: Density of the fluid (mercury)
  • g: Gravitational acceleration
  • h: Height of the fluid column

Why Mercury?

Mercury is used because of its high density (13.6 g/cm³), which allows for a reasonably short column (~76 cm at sea level). If water were used instead, the column would need to be about 10.3 meters tall!

The Vacuum

The space above the mercury column in the tube is nearly a perfect vacuum (called Torricelli vacuum), containing only a small amount of mercury vapor. This vacuum forms because the atmospheric pressure can only support a column of mercury up to a certain height.