1. Class 11th
Part ---1
Priyanka jakhar
Physics (lecturer )
PHYSICAL WORLD

7. Science :--- The word science comes from a Latin word “scientia” which means
‘to know’.
Science is nothing but the knowledge gained through the systematic
observations and experiments.
Science means organized knowledge.
Albert Einstein called Galileo the “father of modern science.”
Jagdish Chandra Bose, Father Of Modern Science In India.
Natural Sciences can be broadly divided in three branches namely Physics,
Chemistry and biology.
Scientific Method ----are used to observe things and natural phenomena.
• Observations
• Controlled experiments,
• Qualitative and quantitative reasoning,
• Mathematical modeling,
• Prediction and
• Verification or falsification of theories

8. Physics :--- The word physics has its origin in a Greek word fusis meaning ‘nature’.
Physics is a quantitative science, where we measure various physical
quantities during experiments.
Sanskrit equivalent of the word Physics is Bhautiki that is used to refer to the study of the physical
world
Physics is the most basic science, which deals with the study of nature and
natural phenomena.
Physics is an empirical study.
Physics is the study of physical world and matter and its motion through space
and time, along with related concepts such as energy and force.
“Physics is the king of all sciences as it helps us understand the way nature
works. It is at the centre of science.
Principal thrusts in Physics
• There are two principal thrusts in Physics
• 1.Unification 2. reduction

9. Two principal types of approaches in Physics are:
1. Unification: This approach considers all of the world’s phenomena as a
collection of universal laws in different domains and conditions.
Example, law of gravitation applies both to a falling apple from a tree as well as
motion of planets around the sun.
Electromagnetism laws govern all electric and magnetic phenomena.
2. Reduction:--- This approach is to derive properties of complex systems from the
properties and interaction of its constituent parts.
Example, temperature studied under thermodynamics is also related to average kinetic energy
of molecules in a system (kinetic theory).
In Physics, there are two domains of interest macroscopic and microscopic.
Macroscopic domain:--- It includes phenomena at the laboratory, terrestrial and astronomical
scales.
Microscopic domain:--- It includes atomic, molecular and nuclear phenomena.
Mesoscopic domain:--- However, recently a third domain of interest between macroscopic
domain and microscopic domain (Mesoscopic) has also come in light.

10. In this domain scientists deals with a few tens or hundreds of atoms, has emerged as an exciting
field of research.
Macroscopic Domain ----Macroscopic domain includes phenomena at large scales
like laboratory, terrestrial and astronomical.
It includes following subjects:
1. Mechanics – It is based on Newton’s laws on motion and the laws of
gravitation. It is concerned with motion/equilibrium of particles, rigid and
deformable bodies and general system of particles.
Examples, a. Propulsion of rocket by ejecting gases
b. Water/Sound waves
2. Electrodynamics – It deals with electric and magnetic phenomena associated
with charged and magnetic bodies.
Examples, a. motion of a current-carrying conductor in a magnetic field
3. Optics – It deals with phenomena involving light.
Examples, a. Reflection and refraction of light
b. Dispersion of light through a prism

11. 4. Thermodynamics – It deals with systems in macroscopic equilibrium and
changes in internal energy, temperature, entropy etc. of systems under
application of external force or heat.
Examples, a. Efficiency of heat engines
b. Direction of physical and chemical process
Microscopic Domain------- Microscopic domain includes phenomena at minuscule
scales like atomic, molecular and nuclear.
It also deals with interaction of probes like electrons, photons and other
elementary particles. Quantum theory has been developed to handle these
phenomena.
Modern Physics Refers to the concepts in physics that have surfaced since the
beginning of the 20th century.
1. Quantum mechanics-- The study of the discrete nature of phenomena at the
atomic and subatomic levels.
2. Atomic physics-- The branch of physics which deals with the structure and

12. properties of the atom.
3. Nuclear physics ---The branch of physics which deals with the
structure, properties and reaction of the nuclei of atoms.
4. Condensed matter physics ---The study of the properties of
condensed materials (solids, liquids and those intermediate between
them and dense gas).
It branches into various sub-divisions including developing fields such
as nano science, photonics etc.
It covers the basics of materials science, which aims at developing
new material with better properties for promising applications.
5. High energy physics --The study of the nature of the particles.