Quantum physics helps us to understand how energy is used or released by atoms. Negatively charged electronics circle around the positively charged nucleus of the atom.
They stay in the same orbit, each having its own level of energy. When, more energy is added, for example, when the atom is heated or when light shines on it, the electron jumps out to another orbit, absorbing the extra energy and drops back this energy in the form of heat or light when its returns back in it’s original orbit. This tiny packet of energy, which every atom possesses is called a ‘Quantum’.
Below Quantum info from Wikipedia (Read More):-
In physics, a quantum (plural: quanta) is an indivisible entity of a quantity that has the same units as the Planck constant and is related to both energy and momentum of elementary particles of matter (called fermions) and of photons and other bosons. The word comes from the Latin "quantus", for "how much." Behind this, one finds the fundamental notion that a physical property may be "quantized", referred to as "quantization". This means that the magnitude can take on only certain discrete numerical values, rather than any value, at least within a range. There is a related term of quantum number.
http://en.wikipedia.org/wiki/Quantum
