Physical World Class 11 Notes Physics Chapter
1
1. Science
Science is a systematic and organised attempt to acquire knowledge about the
surroundings through observations, experiments and verification.
2. Scientific
Method
Several inter-related steps are involved in scientific method. Some of the most
significant steps are as follows:
·
The systematic observations
·
Reasoning
·
Mathematical modelling
·
Theoretical prediction
3. Physics
Physics is a fundamental science concerned with understanding the natural
phenomena that occur in our universe.
It has many branches such as Mechanics, Electromagnetism, Thermodynamics, Modem
Physics, etc. Between 1600 and 1900, three broad areas were developed, which is
together called Classical Physics. These three areas of study are classical
mechanics, thermodynamics and electromagnetism. But by 1905 it became apparent
that classical ideas failed to explain several phenomena. Then some new
theories were developed in what is called Modem Physics such as Special
Relativity, Quantum Mechanics, etc.
4. Scope
and Excitement of Physics
The scope of Physics is very broad and covers a wide range of magnitude of
physical quantities such as length, mass, time, energy, etc.
It deals with the macroscopic world like galaxies and universe as well as
microscopic world like nucleus of an atom and fundamental particles like
electrons, protons, neutrons etc.
Immense excitement is involved in the study of physics since it explains every
naturally occuring phenomena with a set of rules, so that clear understanding
can be achieved. The challenge to carry out imaginative new experiments to
unlock the secrets of nature, to verify or refute theories, is really exciting.
5. Physics
in Relation to Other Sciences
Physics is a very significant branch of science which plays a crucial role in
understanding the developments pertaining to the other branches of science such
as Chemistry, Biology etc.
(i) Physics in relation to Mathematics. Study of physical variables led to the idea of
differentiation, integration and differential equation. Meaningful
interpretation of Mathematics becomes Physics.
(ii) Physics in relation to Chemistry. The concept of X-ray diffraction and radioactivity
has helped to distinguish between the various solids and to modify the periodic
table.
Understanding the bonding and the chemical structure of substances is easy with
the help of the concept of interactions between various particles.
(iii) Physics in relation to Astronomy. Optical telescopes of reflecting and refracting type
enabled man to explore the space around. Discoveries like radio telescopes have
revolutionised the study of Astronomy.
(iv) Physics in relation to Biology. The conceptual study of pressure and its measurement
has helped us to know blood pressure and hence the functioning of heart.
Invention of X-rays developed the field of diagnosis. Electron and optical
microscopic designs have revolutionised the study of medical science.
(v) Physics in relation to Meteorology. The discoveries regarding the study of pressure
variations help us to forecast the weather.
Various other inventions of physics have opened new vistas of study in the
field of sciences and social sciences.
6. Physics
in Relation to Technology and Society
Advancement in physics has led to new technologies and vice-versa. Sometimes
technology gives rise to new dimension of physics; at other times physics
generates new technology. In fact, the technological development is closely
related to the application of science and physics in particular. Physics has a
dominant influence on society. It has helped the human being to develop its
ideas. Development of digital communication systems, rapid mass transport
system, lasers making bloodless surgeries, etc., has made human life easy and
pleasant.
·
There are four fundamental forces in nature
that govern the diverse phenomena of the microscopic and macroscopic world.
These are the ‘gravitational force’, the ‘electromagnetic force’; the ‘strong
nuclear force’, and the ‘weak nuclear force’. Unification of forces is a basic
quest in physics. The electromagnetic and the weak nuclear forces have now been
unified and are seen as aspects of a single ‘electro-weak’ force. Attempts are
being made to unify electro-weak and the strong force.
·
Conservation of energy, momentum, angular
momentum, charge, etc., are considered to be the fundamental laws in physics.
Conservation laws have a deep connection with symmetries of nature. Symmetries
of space and time, and other types of symmetries play a central role in modem
theories of fundamental forces in nature.
7. IMPORTANT
TABLES
Table 1.1 Some Physicists from Different Countries of the World and their Major
Contributions
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