Describe the objective, apparatus and results of the Cavendish experiment
http://en.wikipedia.org/wiki/Cavendish_experiment
http://lmgtfy.com/?q=Cavendish+experiment
The Cavendish experiment, performed by English physicist Henry Cavendish in 1797-1798, was one of the earliest experiments to determine the value of the gravitational constant (G) and to measure the mass of the Earth.
Objective:
The primary objective of the Cavendish experiment was to measure the gravitational constant, which quantifies the force of gravity between two masses. This constant is important in understanding the laws of gravitation and its value has implications for various fields of physics.
Apparatus:
To conduct the experiment, Cavendish used a torsion balance or torsion pendulum apparatus. This consisted of a horizontal bar suspended from a thin wire or fiber, with two small lead spheres (masses) attached to each end of the bar. There were also larger lead spheres placed close to the smaller spheres, but not in contact with them. The entire setup was enclosed in a case to minimize external influences.
Results:
By measuring the slight twisting of the torsion balance due to the gravitational attraction between the large and small lead spheres, Cavendish was able to indirectly measure the gravitational force between them. The twisting of the wire indicated a very small torque caused by this force.
Cavendish recorded the observed shift in the position of a beam of light reflected off the torsion balance, which provided an indication of the rotational motion. By carefully analyzing these measurements, he was able to determine the gravitational constant and ultimately estimate the mass of the Earth.
Overall, the Cavendish experiment laid the foundation for accurately calculating the value of G and furthered our understanding of the fundamental laws of gravity.