11th Class

There are four fundamental forces which govern both macroscopic and microscopic phenomena. There are
(i) Gravitational force
(ii) Nuclear force
(iii) Electromagnetic force
(iv) Weak force

The relative strengths of these forces are Fg : Fw : Fe : Fs = 1::.

All those quantities which can be measured directly or indirectly and in terms of which the laws of physics can be expressed are called physical quantities.
(a) Fundamental quantities
(b) Derived quantities.

The units of the fundamental quantities

Scope of Physics
The Importance of Physics to Society

Physics - the study of matter, energy and their interactions - is an international enterprise, which plays a key role in the future progress of humankind. The support of physics education and research in all countries is important because:



Physics is an exciting intellectual adventure that inspires young people and expands the frontiers of our knowledge about Nature.

Physics generates fundamental knowledge needed for the future technological advances that will continue to drive the economic engines of the world.

Physics contributes to the technological infrastructure and provides trained personnel needed to take advantage of scientific advances and discoveries.

Physics is an important element in the education of chemists, engineers and computer scientists, as well as practitioners of the other physical and biomedical sciences.

Physics extends and enhances our understanding of other disciplines, such as the earth, agricultural, chemical, biological, and environmental sciences, plus astrophysics and cosmology - subjects of substantial importance to all peoples of the world.

Physics improves our quality of life by providing the basic understanding necessary for developing new instrumentation and techniques for medical applications, such as computer tomography, magnetic resonance imaging, positron emission tomography, ultrasonic imaging, and laser surgery.

In summary, for all these reasons, physics is an essential part of the educational system and of an advanced society. We therefore urge all governments to seek advice from physicists and other scientists on matters of science policy, and to be supportive of the science of Physics. This support can take many forms such as:



National programs to improve physics teaching at all levels of the educational system.

Building and maintaining strong departments in universities (and other academic institutions) with opportunities for grants to support research.

Scholarships and fellowships for both undergraduate and graduate students studying physics.

Adequate funding for national laboratories and the formation of new ones as appropriate.

Funding and facilitating international activities and collaborations.

Scope of Physics is vast as it covers quantities with length magnitude as high as 10^40m or more (astronomical studies of universe) and as low as 10^-14m or less (study of electrons, protons etc). Similarly the range of time scale goes from 10^-22s to 10^18s and mass from 10^-30kg to 10^55kg.

Physics is broadly divided into two types based on its scope - Classical Physics and Modern Physics. Classical physics deal with the macroscopic phenomena while the modern physics deals with the microscopic phenomena.


Macroscopic Domain
Classical Physics:


Classical physics includes the traditional branches and topics that were recognized and well-developed before the beginning of the 20th century—classical mechanics, acoustics, optics, thermodynamics, and electromagnetism. Classical mechanics is concerned with bodies acted on by forcesand bodies in motion and may be divided into statics (study of the forces on a body or bodies not subject to an acceleration), kinematics (study of motion without regard to its causes), and dynamics (study of motion and the forces that affect it); mechanics may also be divided into solid mechanicsand fluid mechanics (known together as continuum mechanics), the latter including such branches as hydrostatics, hydrodynamics, aerodynamics, andpneumatics. Acoustics is the study of how sound is produced, controlled, transmitted and received. Important modern branches of acoustics includeultrasonics, the study of sound waves of very high frequency beyond the range of human hearing; bioacoustics the physics of animal calls and hearing, and electroacoustics, the manipulation of audible sound waves using electronics. Optics, the study of light, is concerned not only withvisible light but also with infrared and ultraviolet radiation, which exhibit all of the phenomena of visible light except visibility, e.g., reflection, refraction, interference, diffraction, dispersion, and polarization of light. Heat is a form of energy, the internal energy possessed by the particles of which a substance is composed; thermodynamics deals with the relationships between heat and other forms of energy. Electricity and magnetism have been studied as a single branch of physics since the intimate connection between them was discovered in the early 19th century; an electric current gives rise to a magnetic field and a changing magnetic field induces an electric current. Electrostatics deals with electric charges at rest, electrodynamicswith moving charges, and magnetostatics with magnetic poles at rest.

Macroscopic domain includes phenomena at large scales like laboratory, terrestrial and astronomical. It includes following subjects:

1. Mechanics –

Scope of Physics
The Importance of Physics to Society

Physics - the study of matter, energy and their interactions - is an international enterprise, which plays a key role in the future progress of humankind. The support of physics education and research in all countries is important because:



Physics is an exciting intellectual adventure that inspires young people and expands the frontiers of our knowledge about Nature.

Physics generates fundamental knowledge needed for the future technological advances that will continue to drive the economic engines of the world.

Physics contributes to the technological infrastructure and provides trained personnel needed to take advantage of scientific advances and discoveries.

Physics is an important element in the education of chemists, engineers and computer scientists, as well as practitioners of the other physical and biomedical sciences.

Physics extends and enhances our understanding of other disciplines, such as the earth, agricultural, chemical, biological, and environmental sciences, plus astrophysics and cosmology - subjects of substantial importance to all peoples of the world.

Physics improves our quality of life by providing the basic understanding necessary for developing new instrumentation and techniques for medical applications, such as computer tomography, magnetic resonance imaging, positron emission tomography, ultrasonic imaging, and laser surgery.

In summary, for all these reasons, physics is an essential part of the educational system and of an advanced society. We therefore urge all governments to seek advice from physicists and other scientists on matters of science policy, and to be supportive of the science of Physics. This support can take many forms such as:



National programs to improve physics teaching at all levels of the educational system.

Building and maintaining strong departments in universities (and other academic institutions) with opportunities for grants to support research.

Scholarships and fellowships for both undergraduate and graduate students studying physics.

Adequate funding for national laboratories and the formation of new ones as appropriate.

Funding and facilitating international activities and collaborations.

Scope of Physics is vast as it covers quantities with length magnitude as high as 10^40m or more (astronomical studies of universe) and as low as 10^-14m or less (study of electrons, protons etc). Similarly the range of time scale goes from 10^-22s to 10^18s and mass from 10^-30kg to 10^55kg.

Physics is broadly divided into two types based on its scope - Classical Physics and Modern Physics. Classical physics deal with the macroscopic phenomena while the modern physics deals with the microscopic phenomena.


Macroscopic Domain
Classical Physics:


Classical physics includes the traditional branches and topics that were recognized and well-developed before the beginning of the 20th century—classical mechanics, acoustics, optics, thermodynamics, and electromagnetism. Classical mechanics is concerned with bodies acted on by forcesand bodies in motion and may be divided into statics (study of the forces on a body or bodies not subject to an acceleration), kinematics (study of motion without regard to its causes), and dynamics (study of motion and the forces that affect it); mechanics may also be divided into solid mechanicsand fluid mechanics (known together as continuum mechanics), the latter including such branches as hydrostatics, hydrodynamics, aerodynamics, andpneumatics. Acoustics is the study of how sound is produced, controlled, transmitted and received. Important modern branches of acoustics includeultrasonics, the study of sound waves of very high frequency beyond the range of human hearing; bioacoustics the physics of animal calls and hearing, and electroacoustics, the manipulation of audible sound waves using electronics. Optics, the study of light, is concerned not only withvisible light but also with infrared and ultraviolet radiation, which exhibit all of the phenomena of visible light except visibility, e.g., reflection, refraction, interference, diffraction, dispersion, and polarization of light. Heat is a form of energy, the internal energy possessed by the particles of which a substance is composed; thermodynamics deals with the relationships between heat and other forms of energy. Electricity and magnetism have been studied as a single branch of physics since the intimate connection between them was discovered in the early 19th century; an electric current gives rise to a magnetic field and a changing magnetic field induces an electric current. Electrostatics deals with electric charges at rest, electrodynamicswith moving charges, and magnetostatics with magnetic poles at rest.

Macroscopic domain includes phenomena at large scales like laboratory, terrestrial and astronomical. It includes following subjects:

1. Mechanics –

From walking on the street, to launching a rocket into space, to sticking a magnet on your refrigerator, physical forces are acting all around us. But all the forces that we experience every day (and many that we don't realize we experience every day) can be whittled down to just four fundamental forces:

Gravity. 

The weak force. 

Electromagnetism. 

The strong force. 

These are called the four fundamental forces of nature, and they govern everything that happens in the universe

The International System of Units (SI) consists of seven base units that were adopted worldwide by the General Conference on Weights and Measures (CGPM). These seven units can be found in every aspect of our daily lives and are especially common in the manufacturing sector. In order to innovate, deploy industrial processes, make medical diagnoses, conquer space and much more, it is essential to be able to rely on increasingly precise measurements. So for the past two centuries, metrologists have been continually working to enhance our units of measurement.

The International System of Units (SI) consists of seven base units that were adopted worldwide by the General Conference on Weights and Measures (CGPM). These seven units can be found in every aspect of our daily lives and are especially common in the manufacturing sector. In order to innovate, deploy industrial processes, make medical diagnoses, conquer space and much more, it is essential to be able to rely on increasingly precise measurements. So for the past two centuries, metrologists have been continually working to enhance our units of measurement.