JEE Advanced Modern Physics Important Questions

Every atom consists of a tiny, positively charged centre containing the neutrons (neutral) and protons (positively charged), which is called the nucleus. The branch of physics that deals specifically with the study of the nucleus and its behaviour is known as Nuclear physics. Before diving deep into nuclear physics, it is important to get the basics right and understanding the following terms will help with exactly that:

• Isotopes: Atoms having the same value of atomic number ( the number of protons in an atom, denoted by Z) but a different value of atomic mass number ( the sum of the number of protons and neutrons in an atom, denoted by A) are known as Isotopes.

• Isobars: Exactly the opposite of Isotopes, Isobars are the atoms that have the same mass number (A) but a different atomic number (Z)

• Isotones: The Atoms that have a different atomic number despite having the same number of neutrons are known as Isotones.

• Nature of the Nuclear force: It is on the four fundamental forces in Nature and has properties of its own like being attractive, charges independent, short-range etc. These must be studied in detail before learning more things.

The discovery of the atom was certainly not a short process and it took a lot of years and dedicated efforts of a lot of scientists in order to reach a widely accepted model of the atom. Various scientists provided their own models and were further proven either correct or wrong by future scientists. However, the most important ones of them from an exam point of view are:

1. ‘Plum Pudding Model’ as proposed by J.J Thompson in 1904.

2. Rutherford’s atomic model (derived from the α-particle scattering experiment)

3. The atomic model provided by Neil Bohr, known as Bohr’s atomic model.

Students are expected to know both the advantages and the drawbacks of each of these theories.

As we all know, an atom is considered to be electrically neutral. When an atom develops a charge, be it positive or negative, it can no longer be termed as an atom but is instead called an ‘ion’. The difficulty with which this process takes place, that of removing an electron from an atom that turns it into an ion is known as the Ionization Energy of that atom. This endothermic process usually takes place when the atoms are in their ground state. More the difficulty is to remove an electron, the higher the ionization potential. This can also be further studied as First Ionization Energy and Second Ionization Energy, which basically mean the energy required to remove the first and second electron respectively.

The Photoelectric effect is one of the most commonly asked upon questions both in the mains and advanced and students can almost be certain of expecting at least one question about it in their exam. Without the use of complex jargon, the Photoelectric effect is basically the phenomenon where electrons are emitted from the surface of a metal when light rays are incident upon it. The emission of electrons is directly proportional to the intensity of the light that is incident on the metallic surface.

That about sums it up for this article where we discussed the answers to some of the most frequently asked questions by students regarding this topic and of course, took a look at some interesting problems based on the Modern Physics module of the JEE Advanced. To get access to more such articles and study material, along with regular updates about JEE Mains and advanced, make sure to follow us on