Particle Theory Of Light example essay topic

Many incredible theories about the structure of the atom arose during the turn of the 20th century. Physicists from across the globe searched for answers to so many unknown ideas about the atom. Each time a new idea came about the questions would not stop there. It would only lead to another hypothesis and therefore lead to another quest to find answers. Though the rest of the world was reluctant to embrace the new ideas of the physicists of their time, the theories developed were important steps in understanding the structure of the atom. Sir Joseph John Thomson (J.J. Thomson) discovered the electron in 1897.

His experiment consisted of a stream of electrons, which he directed through an evacuated glass tube at a fluorescent screen producing a small pinpoint of light where the beam struck the screen. He placed a magnet on the side of the tube and was able to deflect the stream of electricity so that the dot jumped downward. This discovery opened a door on the world of subatomic physics. Physicists found his experiment stunning. The deconstruction of the atom into subatomic particles had begun. Physicists now searched deeper.

Ernest Rutherford paid close attention to the science of radioactivity. He studied the manner in which alpha particles scattered when fired at gold foil. Rutherford asked the question, 'can alpha particles be scattered though a large angle' A research done by Ernest Marsden helped answer this question. Since Rutherford had a firm grasp of the sizes, speeds, and masses involved in atoms, Marsden's experiment astonished him. Around Christmas 1910, Rutherford discovered the atomic nucleus. He understood that is was positively charged since alpha particles fired at it did a quick u-turn when they got near the center.

From this, the invisible world turned into the physicists' principal domain. With Albert Einstein's theory of relativity, the rigid framework of space and time, which was th skeleton of classical physics, was destroyed. Einstein thought of the atom as a tangible object, while Rutherford believed it to be the nucleus and its electrons dancing an arcane minuet. With this theory, Rutherford pulled the rug under the feet of the world and stunned them. The question that now arose was how the electrons were arranged around the nucleus.

This is the problem of modern atomic theory. It was concluded that Rutherford's method was too brutal. Instead, light rays were the substitute. From Isaac Newton's idea that light travels in particles, a hundred years later the theory had changed into the idea that light travels in waves. The idea came from the phenomenon of destructive interference. Waves can cancel each other out, but particles cannot.

Max Planck took this idea to its next level. He was interested in color and came up with the particle theory of light. Planck produced a formula for the relation between color and temperature. He stated that a hot body emits light and radiant heat in discrete bundles of energy. This led to Planck's Law and Planck's constant, which we still use today. In 1909, Einstein built on Planck's discovery.

He suggested that light comes from bundles or corpuscles, which he called quanta. While Planck assumed that light is emitted by hot bodies in the form of discrete bundles, Einstein concluded that it always consists of such bundles. From this, color, wavelength, frequency, and energy became almost interchangeable concepts when describing light. Instead of the term light quanta, Gilbert Newton Lewis changed the concept to photons. The first successful attempt to describe the atom was done by Niels Bohr in 1913. He came up with the Bohr model, which he modeled after the planets revolving around the sun.

This wasn't enough to complete his model so Bohr was forced to go beyond the idea of the solar system. In his model, the orbits are set and the speed and energy are easy to compute. He concluded that the larger the orbit of an electron is the higher its energy level will be. Bohr's model marked another triumph for atomism. The structure of every physical phenomenon could be understood in terms of the motion of particles. But Bohr's theory still left unanswered questions.

In 1924, Louis de Broglie studied the relationship between frequency and energy. In his study, he pictured an electron as a wave traveling through a narrow canal. If the canal were curved into a circle, it would self-destruct because of interference. De Broglie further explained Bohr's model by using the idea of wave-like nature.

Bohr's model used point particles, but de Broglie's theory was that it was both particle and wave, a wave-particle. With this, de Broglie changed the world's picture of the atom. Even though the world was skeptical about accepting the ideas of these physicists, the ideas that have developed from these minds have been historic. Without them, the atom's structure would probably still be a mystery.