The Foucault’s Pendulum

Subject : Science and technology

Section: Msc

Concept :

The Foucault’s Pendulum has been installed hanging from a skylight at the top of the Constitution Hall in the newly inaugurated Parliament.
Suspended from the ceiling of the Central Foyer of India’s new Parliament building, inaugurated is a Foucault pendulum.

Foucault’s Pendulum

The Foucault’s Pendulum was named after French physicist Léon Foucault who invented it in the mid-19th Century.
Foucault in 1851 built the first-of-its-kind pendulum comprising a 28-kilo iron ball and a 67-metre steel wire.
Foucault hung the pendulum inside France’s Panthéon and then pushed it to one side and released it – after which it began swinging back and forth.
Though the pendulum swings back and forth the Earth rotates beneath it. This means relative motion is at play.
At the North Pole, latitude 90° N, the relative motion as viewed from above in the plane of the pendulum’s suspension is a counterclockwise rotation of the Earth once approximately every 24 hours (more precisely, once every 23 hours 56 minutes 4 seconds, the length of a sidereal day). Correspondingly, the plane of the pendulum as viewed from above appears to rotate in a clockwise direction once a day.
A Foucault pendulum always rotates clockwise in the Northern Hemisphere with a rate that becomes slower as the pendulum’s location approaches the Equator.
Foucault’s original pendulums at Paris rotated clockwise at a rate of more than 11° per hour, or with a period of about 32 hours per complete rotation.
The rate of rotation depends on the latitude.
At the Equator, 0° latitude, a Foucault pendulum does not rotate.
In the Southern Hemisphere, rotation is counter-clockwise.
In short, as the Earth rotates on its axis the pendulum changes the direction it swings in.

The pendulum inside the new Parliament

Created by the National Council of Science Museum (NCSM) in Kolkata, the pendulum is being dubbed as the largest such piece in India, 22 metre in height, and weighing a staggering 36 kg.
The piece has been crafted with gunmetal and affixed with an electromagnetic coil to ensure hassle-free movement.
It touches the floor as it rotates on its axis. The pendulum hangs from a skylight at the top of the Constitution Hall, and signifies the “integration of the idea of India with the idea of the cosmos.
At the latitude of the Parliament, it takes 49 hours, 59 minutes, and 18 seconds for the pendulum to complete one rotation, as per the details displayed at the installation.