Proton to proton attraction
We know that like charges repel and unlike charges attract. Then in atoms why are protons not repelling when they are so close to each other?
P. NARESH KUMAR
Hyderabad
The repulsion between two bodies causes them to move away from each other. Such a phenomenon takes place when two bodies similarly charged are brought close to each other and if they carry unlike charges, they attract. This has been observed as early as 600 BC by the Greeks, but was formulated precisely, in the 18th century AD, by Coulomb who made large number of quantitative and systematic observations, which led to the now well-known Coulomb’s law. There does exist a force between all charged bodies according to this law.
In an atom, the electrons revolve around the centrally placed nucleus made up of the positively charged protons and the electrically neutral neutrons, together known as nucleons. The nucleus is about hundred thousand times smaller than the orbits of the electrons, implying that the distance between the nucleons is very small as compared to the distance between the electrons and the nucleus.
Truly, the negatively charged electrons in an atom are attracted towards the positively charged nucleus. In the same manner, the positively charged protons do get repelled from each other according to Coulomb’s law.
However, the distance between two such protons is extremely small; about one million times smaller than the distance between the electron and the nucleus. And at such extremely short distances, another kind of force comes into play.
This is known as the nuclear force, which is distinguished from Coulomb’s electrostatic force, by some characteristic features.
Although certain aspects of the exact nature of the nuclear force form topics of current research, by now it is well known to physicists that the nuclear force is attractive, very strong and independent of the charge of the objects. Thus, the electrically neutral neutrons and the protons alike are held bound in the nucleus by this strong force.
A pair of protons inside the atomic nucleus, experience two forces, one, the repulsive electrostatic Coulomb’s force and, two, the attractive and very strong nuclear force. Therefore, the net effect is the strong attraction between them, keeping them inside the nucleus.
Dr. H. K. SAHU
Scientific Officer
Indira Gandhi Centre for Atomic Research
Kalpakkam, Tamil Nadu
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