Foucault

Definition

Foucault was a French physicist who demonstrated the Earth's rotation using a pendulum, known as Foucault's pendulum. His experiments provided direct visual evidence of Earth's rotation in the mid-19th century.

5 Must Know Facts For Your Next Test

1. Foucault's pendulum demonstrates the rotation of the Earth through its predictable change in swing direction over time.
2. The experiment was first publicly demonstrated by Léon Foucault in 1851 at the Paris Observatory.
3. The plane of oscillation of a Foucault pendulum appears to rotate due to the Coriolis effect.
4. The rate of precession of the pendulum depends on the latitude where it is located; it completes a full rotation every 24 hours at the poles and does not rotate at all at the equator.
5. Foucault also invented the gyroscope, another device that demonstrates rotational motion and stability.

Review Questions

• What physical principle allows Foucault's pendulum to demonstrate Earth's rotation?
• How does the latitude of a location affect the precession rate of a Foucault pendulum?
• In what year did Léon Foucault first publicly demonstrate his famous pendulum experiment?

Related terms

Coriolis Effect: An apparent force caused by Earth's rotation that affects wind and water currents.

Gyroscope: A device used for measuring or maintaining orientation, based on principles of angular momentum.

Pendulum: A weight suspended from a pivot so that it can swing freely, often used to regulate devices like clocks.