India’s recently unveiled Parliament building features a unique blend of artistry and science, highlighted by a Foucault pendulum hanging from its ceiling. The pendulum serves not just an aesthetic function, but represents the spirit of scientific inquiry encapsulated in Article 51A of the Indian Constitution.
What is a Foucault Pendulum?
A Foucault pendulum, named after Leon Foucault, a French physicist from the 19th century, is a straightforward experiment designed to illustrate Earth’s rotation. This experiment involves a heavy object suspended on a long wire, swinging freely in any direction. As the pendulum moves to and fro, it appears to gradually change its orientation due to the relative motion between the pendulum and the rotating Earth.
This intriguing experiment was first publicly performed by Foucault in 1851 at Paris’ Pantheon, where he hung a 28-kg iron ball from a 67-m wire. It provided the first direct visual proof of Earth’s rotation. The experiment proved that the “pendulum does not change its plane of motion, but the ground beneath it does.”
Understanding the Pendulum’s Motion Relative to Earth’s Rotation
When the pendulum is aligned with the Earth’s axis at the north and south poles, it takes exactly 24 hours for the back-and-forth motion to return to its starting point. However, at other latitudes, it takes longer as the pendulum is not aligned with the Earth’s axis.
The rate and direction at which the pendulum appears to rotate are influenced by its latitude. For instance, at the North Pole, it would make one clockwise rotation every 24 hours. Conversely, at the equator, there would be no perceived rotation. Latitudes in between these extremes would witness intermediate rates and directions of rotation.
The Special Significance of the Pendulum in the New Parliament Building
The National Council of Science Museum (NCSM) in Kolkata crafted the pendulum in the new Parliament building. Standing as the largest of its kind in India, the pendulum measures 22m in height and weighs 36 kg.
Strategically hung from a skylight at the apex of the Constitution Hall, the pendulum represents the fusion of India’s ideology with cosmic concepts. At the latitude of Parliament located in New Delhi (28.6° N), it takes nearly 49 hours and 59 minutes for the pendulum to make one full clockwise rotation.
