Foucault pendulum

<p>The Foucault pendulum or Foucault's pendulum is a simple device named after French physicist <a href="/facts/L%25C3%25A9on_Foucault/xG7tEDjk">Léon Foucault</a>, conceived as an experiment to demonstrate the <a href="/facts/Earth%2527s_rotation/mDbXcKUx">Earth's rotation</a>. If a long and heavy pendulum suspended from the high roof above a circular area is monitored over an extended period of time, its <a href="/facts/Plane_(geometry)/tAUtRFcn">plane</a> of <a href="/facts/Oscillation/6vSrm84a">oscillation</a> appears to change spontaneously as the Earth makes its 24-hourly rotation. This effect is greatest at the poles and diminishes with lower latitude until it no longer exists at Earth's <a href="/facts/Equator/CjaxbVaN">equator</a>.
</p><p>The <a href="/facts/Pendulum/D2hQXwlI">pendulum</a> was introduced in 1851 and was the first experiment to give simple, direct evidence of the Earth's rotation. Foucault followed up in 1852 with a <a href="/facts/Foucault%2527s_gyroscope_experiment/D8y2U1Nr">gyroscope experiment</a> to further demonstrate the Earth's rotation. Foucault pendulums today are popular displays in <a href="/facts/Science_museum/tSuCPQ1l">science museums</a> and universities.
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Foucault pendulum open-in-new

Foucault pendulum