Period of Rotation of Plane of Oscillation of Foucault's Pendulum/Mistake

Source Work

1998: David Nelson: The Penguin Dictionary of Mathematics (2nd ed.)

2008: David Nelson: The Penguin Dictionary of Mathematics (4th ed.):

Foucault's pendulum

Mistake

To an observer on earth the plane of oscillation [of Foucault's pendulum] makes one rotation every $24$ hours (approximately).

Correction

An oversimplification.

At Earth's poles, the period of rotation of the plane of oscillation of Foucault's pendulum is $1$ sidereal day, which is $23$ hours, $56$ minutes and $4.0916$ seconds.

Elsewhere on Earth, the period $T$ of rotation of the plane of oscillation depends on the latitude at which the pendulum is located:

$T = \dfrac D {\sin \lambda}$

where:

$\lambda$ is that latitude

$D$ denotes the length of a sidereal day.

Sources

• 1998: David Nelson: The Penguin Dictionary of Mathematics (2nd ed.) ... (previous) ... (next): Foucault's pendulum
• 2008: David Nelson: The Penguin Dictionary of Mathematics (4th ed.) ... (previous) ... (next): Foucault's pendulum