Introduction:
The JEE (Joint Entrance Examination) Main is a highly competitive entrance exam conducted in India for admission to undergraduate engineering programs. The physics section of the JEE Main exam covers a wide range of topics, including modern physics, which includes quantum mechanics and nuclear physics.

Coverage of Modern Physics:
The JEE Main physics section typically includes questions from various topics, and modern physics is one of them. It is an important and significant part of the syllabus, and candidates can expect questions from this area. Modern physics covers topics such as quantum mechanics, nuclear physics, and special theory of relativity.

Quantum Mechanics:
Quantum mechanics is a fundamental theory that describes the behavior of particles at the atomic and subatomic level. It is the branch of physics that deals with the wave-particle duality, uncertainty principle, and the wavefunction. In the JEE Main exam, questions can be asked on topics such as:

1. Wave-particle duality: Questions may involve the concept that particles can exhibit both wave-like and particle-like properties.

2. Particle in a box: Questions may be based on the concept of a particle confined within a potential well and its energy levels.

3. Quantum numbers: Questions may test the understanding of quantum numbers and their significance in describing the properties of particles.

4. Schrödinger equation: Questions may involve solving the time-independent Schrödinger equation for simple systems.

Nuclear Physics:
Nuclear physics is the branch of physics that deals with the study of atomic nuclei and their properties. In the JEE Main exam, questions can be asked on topics such as:

1. Nuclear reactions: Questions may involve understanding nuclear reactions, including fusion, fission, and radioactive decay.

2. Nuclear binding energy: Questions may test the knowledge of calculating the binding energy of a nucleus and its relation to nuclear stability.

3. Radioactivity: Questions may be based on the different types of radioactive decay, such as alpha decay, beta decay, and gamma decay.

4. Nuclear models: Questions may involve understanding the different nuclear models, such as the liquid drop model and the shell model.

Conclusion:
In conclusion, candidates appearing for the JEE Main exam can expect questions from modern physics, including topics like quantum mechanics and nuclear physics. It is important to thoroughly study and understand these topics to perform well in the physics section of the exam.