So closely related to atomic physics, nuclear physics is the branch of physics that deals with the physics of nucleus, there are various applications of nuclear physics in today’s world. This branch is perhaps the most important branch and has applications in nuclear power generation and nuclear weapons technology, but the research has provided application in many fields, including those in nuclear medicine and MRI scans, ion implantation in materials engineering, and radiocarbon dating in geology and archaeology.
The nucleus was discovered by Rutherford’s team in 1911. The experiment stated that most of the atom is an empty space and most mass of the atom was concentrated in the centre of the atom which consisted of positively charged particles this was called the nucleus. Thus the advent of nuclear physics began.
Discovery of the Neutron
In the year 1932 James Chadwick observed an emission of neutral radiation, this radiation was caused due to a neutral particle which he called neutron.
Nucleus simply explained
For those who have a difficulty understanding the structure of atom, it can be considered as a fruit with all its seeds in the middle and these seeds can be considered as protons and neutrons and in turn it can be considered as a nucleus.
Nuclear Binding energy
The atom as a whole consists of electrons, neutron and protons in the nucleus.
Now here’s a question that will make you scratch your heads:-
How does the nucleus remain intact despite the tremendous repulsive force between the protons and neutrons?
The answer obviously lies in Binding energy.
Nuclear Binding Energy
In the year 1905 physicist Dr. Albert Einstein published his Special Theory of Relativity, which gave birth to his famous equation E=mc^2 .
Now the specialty of this equation is that it gives the amount of energy that is equivalent to an amount of mass multiplied by the square of speed of light (3×10^8 m/s).
I know guys this may sound very absurd to you at first, in order to know more about the equation and special relativity please have a look at special relativity from the website itself.
Now if we try to calculate the amount energy present in say 2g of a substance, we have here:-
Hence so much amount of energy is more than enough to overcome the repulsion in the nucleus hence the nucleus stays intact.
But there’s a catch here my friends, while doing calculations with nucleus. The mass taken in the equation is not the entire mass of the nucleus but it is the difference in the total mass of nucleus and its constituents. This is called the mass defect, mass defect is again a consequence of the theory of relativity where the constituents of the nucleus undergo the mass-energy conversion and convert into energy.
The nuclear force is the between two or more nucleons meaning between protons and neutrons. This is one of the strongest forces in nature that are known to man. The applications of this concept are in nuclear power and nuclear weapons. It is a very short range force.
The basic meaning of radioactive decay is Radioactive decay is the process by which a nucleus of an unstable atom loses energy by emitting particles.
There are 3 types of decays:-
1. Alpha decay (α) – The main thing needed to remember about this decay is that when an element undergoes α decay it emits a helium nucleus i.e. 2 protons and 2 neutrons.
2. Beta decay (β) – When an element undergoes β decay the nucleus emits a β particle (electron or anti electron/positron). There are 2 types of β decays as well, β+ and β-.
3. Gamma decay (γ) – In gamma decay the nucleus changes from higher energy state to lower energy state by emission of photons. The number of protons and neutrons remains unchanged.
Therefore this session of basics of nuclear physics ends here.
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P.S. You don’t have to be a nuclear physicist to understand nuclear physics. 😉