General Physics

Step 1: Analyze the definition provided in the question.
The question asks to identify the force of mutual attraction between two objects that exists "by virtue of their masses." This means the force exists because the objects have mass, and its strength depends on their masses.

Step 2: Compare this definition with the fundamental forces of nature.
There are four fundamental forces: 1. Gravitational force: An attractive force that acts between any two objects with mass. The strength of the force is proportional to the product of the masses. 2. Electromagnetic force: Acts between electrically charged particles. It is not directly dependent on mass. 3. Strong nuclear force: Holds the nucleus of an atom together, acting between protons and neutrons. It is extremely short-range and is not a function of the total mass of an object. 4. Weak nuclear force: Responsible for radioactive decay processes. It is also a very short-range force.

Step 3: Conclude the correct identification.
The definition given in the question perfectly matches the description of the gravitational force. Newton's Law of Universal Gravitation, , explicitly states that this force is due to the masses ( ) of the objects.

The weak nuclear force is one of the four fundamental forces of nature, alongside the strong nuclear force, electromagnetism, and gravitation.
It is responsible for radioactive decay processes like beta decay.
The range of a force is the characteristic distance over which it is effective.
The weak nuclear force has an extremely short range, significantly smaller than the size of an atomic nucleus.
Its range is typically quoted to be on the order of meters to meters.
Among the given options, m is the correct order of magnitude for the range of the weak nuclear force.

Step 1: Understanding the Concept:
Physics is broadly divided into two domains of interest: the macroscopic domain and the microscopic domain.
- The macroscopic domain includes phenomena at the laboratory, terrestrial, and astronomical scales. It deals with objects that are large enough to be seen and handled directly.
- The microscopic domain includes phenomena at the atomic, molecular, and nuclear scales. It deals with the fundamental constituents of matter.
Step 2: Detailed Explanation:
The question asks about the branch of physics concerned with the "constitution and structure of matter at the minute scales of atoms and nuclei."
- This description directly corresponds to the definition of the microscopic domain. Quantum mechanics is the primary theory used to describe this domain.
- Classical physics (Option C) mainly deals with the macroscopic domain, describing the motion of objects, fluids, and waves on a large scale.
- Thermodynamics (Option D) also deals with macroscopic systems in terms of heat, work, and temperature.
Therefore, the study of atoms and nuclei falls squarely within the microscopic domain.
Step 3: Final Answer:
The correct option is (A) because the microscopic domain is the area of physics that studies the structure and behavior of matter on the scale of atoms and nuclei.