• Science means
organized knowledge.
It is human
nature to observe things and happenings
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Example: Phenomena of apple falling to ground,
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moon revolving around earth and weightlessness
in
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around in the
nature and then to relate them. This
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the rocket, all these phenomena are explained
with
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knowledge is
organized so that it become well
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help of one Law that is, Newtons Law of
Gravitation.
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connected and
logical. Then it is known as Science. It
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is a systematic
attempt to understand natural
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Reductionism
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phenomenon and
use this knowledge to predict,
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• To
understand or to derive the properties of a
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modify and
control phenomena.
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bigger or more complex
system the properties
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Scientific Method
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of its simpler constituents are taken into
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Scientific
methods are used to observe things and
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account. This approach is called reductionism.
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It is supposed to be the heart of Physics.
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natural
phenomena. It includes several steps :
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For example a complex thermo dynamical system
can
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•
|
Observations
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be understood by the properties of its
constituent like
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•
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Controlled experiments,
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kinetic energy of molecules and atoms.
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•
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Qualitative
and quantitative reasoning,
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• Mathematical modeling,
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• Prediction and
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• The scope of Physics can be
divided in to two
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•
|
Verification
or falsification of theories.
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domains;
Macroscopic and Microscopic.
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There is
no ‘final’ theory
in science and
no
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unquestioned authority in science.
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• Macroscopic
domain includes phenomena at the
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level of
Laboratory, terrestrial and astronomical
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•
|
Observations
and experiments need theories
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scales.
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to
support them. Sometimes the existing
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• Microscopic domain I ncludes atomic, molecular
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theory is
unable to explain the new
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and
nuclear phenomena.
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observations,
hence either new theories are
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• Recently third domain in between is also
thought
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formed or
modification is done in the existing
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of with
name Mesoscopic Physics. This deals with
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theories.
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group of
Hundreds of atoms
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•
|
For
example to explain different phenomena
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• Scope of physics is very wide and exciting
|
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in light,
theories are changed. To explain
|
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because
it deals with objects of size as large
|
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bending
of light a new Wave-theory was
|
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as Universe (1025m) and as
small as 10-14 m,
|
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formed, and then to explain photoelectric
|
the size
of a nucleus.
|
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effect help of quantum mechanics was taken.
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The excitement of Physics is
experienced in many
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Natural Sciences can be broadly divided in
three
|
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fields Like:
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branches namely
Physics, Chemistry and biology
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• Live transmissions through television.
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•
|
Physics is a
study of basic laws of nature and
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• Computers
with high speed and memory,
|
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their manifestation in different phenomenas.
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• Use of Robots,
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Principal thrusts
in Physics
|
|||
• Lasers and their applications
|
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•
|
There are
two principal thrusts in Physics;
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• 1.Unification 2. reduction
|
Physics in relation to other branches of
Science
|
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Unification
•
Efforts are made to explain different phenomena in nature on the basis
of one or minimum laws. This is principle of Unification.
Physics in relation to Chemistry.
•
Chemical bonding,
atomic number and complex structure can be explained by physics phenomena of
Electrostatic forces,
•
taking help of
X-ray diffraction.
Physics in relation to other Science
•
Physics in relation to Biological Sciences: Physics helps in study of
Biology through its inventions. Optical microscope helps to study bio-samples,
electron microscope helps to
study
biological cells. X-rays have many applications in biological sciences. Radio
isotopes are used in cancer.
•
Physics in
relation with Astronomy:
•
Giant astronomical
telescope developed in physics are used for observing planets. Radio telescopes
have enabled astronomers to observe distant limits of universe.
•
Physics related to
other sciences: Laws of Physics are used to study different phenomenas in other
sciences like Biophysics, oceanography, seismology etc.
Fundamental Forces in Nature
There is a large number of forces experienced or applied. These may be
macroscopic forces like gravitation, friction, contact forces and microscopic
forces like electromagnetic and inter-atomic forces. But all these forces arise
from some basic forces called Fundamental Forces.
Fundamental Forces in Nature..
1. Gravitational force.
•
It is due to Mass
of the two bodies.
•
It is always
attractive.
•
It operates in all
objects of universe.
•
Its range is
infinite
-38
It’s a weaktimes comparedforcetostrong.10 Nuclear force
2.Electromagnetic Forces:
•
It’s due to
stationery charge
•
It may be
attractive or repulsive.
•
It operates on
charged particles
•
Its range is
infinite
•
Its stronger 1036 times than gravitational force but 10-2 times of strong Nuclear force.
3. Strong nuclear force:
•
Its range is very
short, within nuclear size (10-15 m).
•
Its strongest force
in nature
4.Weak Nuclear force:
•
Operate within nucleons I.e. elementary particles like electron and
neutrino.
•
It appears during
radioactive b decay.
•
Has very short
range 10-15m.
•
10-13 times than Strong nuclear force.
Conservation Laws
•
In any physical phenomenon governed by different forces, several
quantities do not change with time. These special quantities are
conserved
quantities of nature.
1.For motion under conservative force, the total mechanical Energy of
a body is constant.
2.Total energy of a system is conserved, and it is valid across all
domains of nature from microscopic to macroscopic. Total energy of the universe
is believed to be constant.
3.Conservation of Mass was considered another conservation law, till
advent of Einstein. Then it was converted to law of conservation of mass plus
energy. Because mass is converted into energy and vice-versa according to
equation E = mc2 The examples are annihilation and pair
production.
4.Momentum is another quantity which is
preserved. Similar is angular momentum of an isolated system. 5.Conservation of
Electric charge is a fundamental law of nature.
6. Later there was development of law of conservation of attributes
called baryon number, lepton number and so on.
or moving
Electrical
The laws of nature do not change with change of space and time. This
is known as symmetry of space and time. This and some other symmetries play a
central role in modern physics. Conservation laws are connected to this.
•
Operate between
Nucleons
•
It may be
attractive or repulsive
