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Quantum Properties of Light
Quantum
properties of light can be explained using the Light emission and absorption
theory at the atomic level as follows:
Light can be emitted
or radiated. This happens by electrons circling around the nucleus of an
atom. Electrons can circle only in restricted patterns called an
“orbital.” Each electron has a specific amount of energy in each
orbital. The amount of energy needed for each orbital is called the
energy level of an atom.
The electrons that have less energy circle
close to the nucleus because those electrons have lesser energy than the ones
that are out further away from the nucleus. Suppose the electron is part
of the lowest orbital, then what happens is that there is no more
radiation even if the electron is moving. Radiation occurs when the
electron has the required power to radiate. But if an electron in the
lower energy orbital gains more energy then it will jump to another level. This
is expressed as an atom getting excited. As a result of the motion, the
electron loses energy and it goes down some orbital levels depending upon
how much power it has lost. In this process the energy that electron
releases is equal to the difference between the higher and lower energy
levels. This difference in energy is emitted in the form of photon.
The electron however may emit a certain amount of energy in a
form of a photon. Since each atom has its unique set of energy levels, their energies correspond with the photons. When that happens they
start emission and that’s called “ atom spectrum.” The spectrum is like a
fingerprint, which can be identified easily. The process of identifying
a substance from its spectrum is called “spectroscopy.” Laws that
describe the orbital and energies are part of the law of the quantum
theory.
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