In 1798, English scientist Henry Cavendish carried out one of the most delicate experiments in history when he “weighed the world.” Using a simple setup of lead spheres suspended by a thin torsion wire, he measured the tiny gravitational attraction between them. This allowed him to calculate the density of the Earth and, indirectly, its total mass, something no one had done before.
Cavendish’s apparatus consisted of a horizontal rod with small lead balls at each end, suspended from a fine wire. Larger stationary lead balls were placed nearby, and the faint twist in the wire caused by gravitational pull was observed with astonishing care. Every movement had to be measured through reflections of light to avoid disturbing the setup, as even breathing near it could ruin the results.
With only 18th century tools, Cavendish’s calculations came within about 1 percent of the modern accepted value for Earth’s mass. His “Cavendish experiment” not only confirmed Newton’s law of universal gravitation but also paved the way for measuring the gravitational constant, a cornerstone of modern physics.
In 1798, Henry Cavendish conducted a groundbreaking experiment that would change the way we understand gravity. Known as the Cavendish experiment, his goal was to measure the gravitational constant (??G) and determine the mass of the Earth. At the time, the nature of gravity was still a mystery, and Cavendish’s experiment was one of the first attempts to measure the gravitational force between objects. This experiment laid the foundation for modern gravitational physics.
The setup of Cavendish's experiment was both simple and ingenious. He used a torsion balance, which consisted of a horizontal rod suspended by a thin wire. Small lead spheres were attached to either end of the rod. Two much larger lead spheres were placed near the smaller ones, and their gravitational attraction caused the rod to twist slightly. This tiny movement was detected and measured, allowing Cavendish to calculate the gravitational force between the spheres.
By carefully analyzing the amount of twist in the rod, Cavendish was able to calculate the gravitational force between the lead spheres. This force was directly related to the mass of the Earth, since gravitational force depends on the mass of the objects involved. Cavendish’s measurements allowed him to determine the gravitational constant (??G) and, using this constant, calculate the mass of the Earth with surprising accuracy. His results were instrumental in validating Newton's law of universal gravitation and provided a crucial step toward a deeper understanding of how gravity works.
The Cavendish experiment was revolutionary because it provided the first accurate measurement of the gravitational constant. Prior to this, gravitational force was a theoretical concept, and its precise value had never been measured. Cavendish’s work not only confirmed the predictions made by Isaac Newton’s theory of gravity but also provided a way to calculate the mass of the Earth itself, which had remained an elusive number up until then. This was a key moment in the history of physics, as it brought measurable precision to a fundamental force of nature.
Today, Cavendish’s experiment is still regarded as one of the most important experiments in physics. It was a pivotal step in our understanding of gravity and the forces that govern the universe. His use of the torsion balance was a brilliant solution to measuring forces that are invisible and incredibly weak, and his work continues to inspire scientists studying gravitational forces. The Cavendish experiment demonstrated the power of precision and experimentation in unlocking the mysteries of nature, shaping the future of physics and astronomy.
Henry Cavendish was a quiet but brilliant English scientist whose careful experiments changed both chemistry and physics. He did not work with one single grand theory but instead built knowledge through precise measurement and observation.
He was the first to clearly identify hydrogen which he called inflammable air. Through experiments he showed that when hydrogen burns it forms water. This proved that water is not an element but a compound made of hydrogen and oxygen.
Cavendish also carried out the famous experiment that measured the density of the Earth. By doing this he helped scientists calculate the mass of our planet for the first time using gravity and careful balance.
In electricity his work came very close to what later became known as Ohm law. He also developed early ideas about electric charge and current long before the field was fully formed.
Even though his work was often hidden during his life it later became clear how important it was. Henry Cavendish laid deep foundations for modern science through patience accuracy and a powerful respect for experimental truth.
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