Modern Physics ( Behavior of Matter and Energy Under Extreme Conditions)
1. Atomic physics and nuclear physics :
It is the study of components, structure, and behavior of the nucleus of an atom
2. Quantum physics :
It is concerned with the study of the individual nature of the phenomena at the atomic levels. It comprises the atomic and sub-atomic systems and also their interaction with radiation
3. Solid-state physics :
It is the study of all the properties of solid materials. It comprises things like electrical conduction in crystals of semiconductors and metals, superconductivity photoconductivity, etc.
4. Relativistic physics :
It is the study of the phenomena that take place in the frame of reference that is in motion with respect to an observer
5. Astrophysics :
It is the physics in the universe that deals with the nature of stars and celestial bodies in astronomy
6. Bio-physics :
It is the study of the physical behavior of the biological process
7. Chemical physics :
It is the science of physical relation in the chemistry
8. Econo-physics :
It deals with the physical process and their relation in the science of economy
9. Geo-physics :
It is the science of physical relations that happen on our planet
10. Medical physics or Biomedical physics :
It is the application, prevention, diagnosis and treatment in the medical field
11. Plasma physics :
It is the plasma, fourth state of matter
12. Low-temperature physics :
It is the study of production and maintenance of the temperature down to almost absolute zero and the various phenomenon which occur only at that temperature
Excitement :
The excitement of physics comes in conducting new experiments, the discovery of the different of the secrets of nature and applying the laws of physics for practical purposes
Basic Forces in Nature :
1. Gravitational forces :
Force of attraction between point masses
2. Electrostatic force :
Force of attraction or repulsion between point charges at the rest
3. Magnetic force :
Force of attraction or repulsion between magnets or magnetic substances
4. Electromagnetic force :
The force between moving charges
5. Nuclear force :
Strong Force between nucleons
6. Weak force :
It is not well understood as yet. the range of this force is even less than that of the other
( NOTE: All the above forces will be discussed in details in respective chapters of class 11 & 12 )
Conservation laws :
In any physical phenomenon governed by different forces, several quantities may change with time, however, some physical quantities remain constant in time. These quantities are conserved quantities in nature. These remarkable facts are the basis of many laws called conservation laws.
1. Law of conservation of linear momentum :
“ The total linear momentum of the objects, in a given direction , before the collision is equal to the total linear momentum of the objects in the same direction after the collision if and only if there is no external force acting on a system of colliding objects”
2. Law of conservation of mass-energy :
“The sum total of mass and energy remains constant in the universe”
3. Law of conservation angular momentum :
“If there is no external torque acting upon a system, the total angular momentum remains constant”
4. Law of conservation of charges :
“The total electric charges of an isolated system remains constant”
5. Law of conservation of energy :
“The total energy of any system remains constant”
( NOTE: There are nearly 14 conservation laws based on symmetry principles in the physics, like the law of conservation of baryons, the law of conservation of leptons,law of conservation of isotopic spin, the law of conservation of strangeness, etc. but they are beyond the syllabus of class 11 & 12 and some conservation laws will be described in details in the coming chapters.)
Physics technology and society :
Technology is the application of various laws, doctrines of physics for a practical purposes. Practical application of physics and other branches of science have played very important role in the development of industry and in improving the standard of living of man.
The understanding of electromagnetic waves in the longer wavelength domain has found applications in radio, televisions and wireless communication.
Televisions program from the distant countries ‘live’ via satellites. The satellite communication has resulted in bringing the world to the tabletop. These satellites also help in forecasting weather and in a geophysical survey such as exploration of oil wells. The electricity that we use in our homes and industry is generated at the power plant by the conversion of some other form of energies into electrical energy.
Nuclear energy released in the fission process is the source of energy in a nuclear reactor that produces electricity.
A host of other applications of the physics have contributed a great deal to the technical advancement of the society. Our society, today is coming more and more science-oriented. Thus physics plays a very significant role in technology and our daily lives.