Physics experiments have changed the world irrevocably, altering our reality and enabling us to take gigantic leaps in technology. From ancient times to now, here’s a look at some of the greatest physics experiments of all time.
Conservation of energy
Energy conservation — the idea that energy cannot be created or destroyed, only transformed — is one of the most important laws of physics. James Prescott Joule demonstrated this rule, the first law of thermodynamics, when he filled a large container with water and fixed a paddle wheel inside it. The wheel was held in place by an axle with a string around it and then looped over a pulley and attached to a weight, which, when dropped, caused the wheel to spin. By sloshing the water with the wheel, Joule demonstrated that the heat energy gained by the water from the wheel’s movement was equal to the potential energy lost by dropping the weight.
Measurement of the electron’s charge
As the fundamental carriers of electric charge, electrons carry the smallest amount of electricity possible. But the particles are truly tiny, with a mass 1,838 times smaller than the already-minuscule proton.
So how could you measure the charge on something so small? Physicist Robert Millikan’s answer was to drop electrically charged oil drops through the plates of a capacitor and adjust the voltage of the capacitor until the electric field it emitted produced a force on some of the drops that balanced out gravity — thus suspending them in the air. Repeating the experiment for different voltages revealed that, no matter the size of the drops, the total charge it carried was a multiple of a base number. Millikan had found the fundamental charge of the electron.
“Gold foil experiment” revealing the structure of the atom
Once thought to be indivisible, the atom was slowly divided and split by a series of experiments during the late 19th and early 20th centuries. These included J.J. Thomson’s 1897 discovery of the electron and James Chadwick’s 1932 identification of the neutron. But perhaps the most famous of these experiments was Hans Geiger and Ernest Marsden’s “gold foil experiment.” Under the direction of Ernest Rutherford, the students fired positively charged alpha particles at a thin sheet of gold foil. To their surprise, the particles passed through, revealing that atoms consisted of a positively charged nucleus separated by a…
Click Here to Read the Full Original Article at Livescience…