Реферат: Electricity Essay Research Paper WHAT IS ELECTRICITYElectricity

Bulk matter is normally neutral. The tendency is for every positive proton in an atom to be electrically balanced against a negative electron, and the sum is as close to zero as anyone has been able to measure. In 1911, Ernest Rutherford proposed the nuclear atom. He suggested that electrons orbit a positively charged nucleus less than 1/100,000,000,000,000 meters in diameter, just as planets orbit the Sun. Rutherford also suggested that the nucleus is composed of protons, each having a charge +e.

This view of matter, still considered correct in many ways, established the electrical force as that which holds an atom together. After Rutherford presented his atom, the Danish physicist Niels Bohr proposed that the electrons have only certain orbits about the nucleus, that other orbits are impossible.

Quantum Theory

Early in the 20th century the quantum theory was developed. According to this theory, the electron is a smeared cloud of mass and charge. In some situations the electron cloud might be so small that the particle appears to be much like the tiny, charged marble of earlier views. In other situations, such as when the electron is in an atomic orbit, the cloud is many times larger.

In 1963, Murray Gell-Mann and George Zweig of the California Institute of Technology proposed a theory according to which the electronic charge e might not be the fundamental charge after all. In their theory, heavy particles such as protons and neutrons consist of various combinations of particles called quarks. One quark is supposed to have charge (-1/3)e and another (-2/3)e. This theory has prompted a major search for quarks.

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