what do you mean by quantization of the radiation?

Answer 1

The basic concept of quantization in physics means that electromagnetic radiation (including light) is composed of quanta, called photons. Each quantum (photon) of electromagnetic energy has a discrete value of energy, which depends on the frequency, E = hf, where E is the energy of the quantum (photon), h is Planck's constant, a very small number, and f is the frequency (cycles per second) of the photon. This concept was developed as part of quantum mechanics. Before quantum mechanics, most physicists considered electromagnetic radiation to be in the form of waves, and observations of macroscopic systems seemed to confirm that. For waves the energy can be continuously varied. But that posed a problem for theoretical thermodynamics. Continuous electromagnetic wave energy also created problems as the physical theory of the atom was developed, and as phenomena on the atomic scale were observed. It had to be recognized that in many ways electromagnetic waves acted as particles of discrete (quantized, not continuous) energy. Consequently, these quanta are now considered to behave as particles in many ways, but also to have some properties of waves. Which they appear to be depends on how they are observed, what type of interaction. On the atomic level they usually acts as particles. Both aspects are inherent properties of the photon (quantum); this is frequently referred to as "duality" in quantum mechanics.

For example, a beam of light that you can see consists of trillions of photons, but these photons were individually created, one at a time, emitted by individual atoms in the light source. An atom emits only one photon at a time, as it decays from an energetic state to a state of less energy (the difference in energy being essentially the photon's energy). (There are rare cases of emitting more than one photon at a time.) It can emit another photon if it takes another step down in energy level, or if it is excited back to the higher energy state and again drops to lower energy. But each decrease of energy is a discrete step, resulting in one photon (quantum) of very small but discrete energy. The wave theory would have allowed the atom to emit smaller amounts of energy, actually any smaller amount, down to infinitesimally small. But this is not what is observed, and it would conflict with other principles of radiation. Therefore, the radiation had to be "quantized" in physical theory, to make the theory consistent with observation, and with other parts of physical theory.

If you know the two energy levels for the atomic transition, you can calculate the frequency of the photon that is emitted, by the above equation, namely f = E / h.

There are additional, more complicated aspects to quantization of radiation, dealing with additional quantum numbers and additional conditions, such as the presence of an external magnetic field. They all are based on the basic concept above.

Answer 2

There are but four fundamental forces in the universe: gravity, electro-magnetic (EM), and strong and weak atomic forces that deal with the binding of atomic nuclei. All four forces can be described as resulting from messenger particles or quanta that carry their respective force messages.

Photons are the most well-known of the messenger particles. They carry the EM force messages. The energy of each photon is determined by E = hf; where h is the Planck constant and f is the fundamental frequency. Bosons and gluons are the messengers for the weak and strong forces respectively.

The messenger particles of gravity (gravitons) and of EM radiate outward like a sphere from their sources. Which is why we can say they are radiation.

The force densities (the force field) for these two forces decrease as the inverse of the square of the distance from their source. This is why F = kqq/R^2, the force from Coulomb's Law, and W = GmM/R^2, the force from Newton's Gravity Law, both have the 1/R^2 factor in them.

The pattern of the strong and weak forces within the atomic cores is somewhat different than the 1/R^2 case. In fact, these forces degrade quite rapidly from their sources and stay within the confines of a nucleus.

Three of the four forces are massless; again, the photons are the most well known of these. Only the boson has mass among the four force messengers.

There are, of course, massive particles or quanta in general. But they do not radiate unless forced to by an outside force.

Answer 3

When an element is divided into parts we end up with fundamental particles like electrons, protons etc.
The fundamental particles cannot be further divided.
They end up with discrete particles.
Hence we can count the number of electrons, number of protons etc.
This is called quantization.
In the case of energy we feel that we cannot count the number of discrete energy particles. {Do not confuse yourself with the units of energy. The units can be varied according to our need]
But in modern physics, it is found that energy also acts like discrete particles. The fundamental particle has an energy represented by the value h.for an electromagnetic wave of frequency 1 Hz. Splitting of this energy into fractions is impossible. If the frequency is n then the fundamental particle of energy is hn.

Since we can count the number of pockets of energy, we say energy is quantized.