Science | Class 11th Notes | Physics | Unit-Physical World And Measurements | Chapter-1| Physical World | part:-1

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Physic for class – XI

Unit -1: Physical world and measurements

What is physics?:-  The modern era is the era of science. The word science is derived from the Latin word scientia, meaning to know.

The curiosity of human is to get more and more information about the objects around him.
Human has gained a lot of information through continuous observations and experimental studies.
According to John Woodburn and E.O.Biran, "Science is the effort of man to make ever-increasing realities, events and circumstances, these conditions and events are subject to our environment."

Bruce Lindsay According to 'the method of describing, generating and explaining human experiences is science."

According to noted scientist Neil Bohr, the work of science is to increase the range of our experiences and reduce their ranking.
[The task of science is both to extend the range of our experience and reduce it to order)
Science is the systematic organization of knowledge received by humans through observations and experiments.
In short, "science is the systematic study of events in the world." The word is derived from Physics, a Greek word meaning: nature.
according to this :"Physics is the science under which nature or natural phenomena are studied. (Physics may be defined as the science which deals with study of nature / natural phenomena). In daily life we see many phenomena, such as the Sun.
Regular rise and fall, seasons of the year (winter, summer, rain), cloud formation and rain, thunderstorms, heat generated by burning coal, movement of moon, moon and solar eclipse, soap bubbles.
Bright colors etc. Humans have always been curious about every event happening in nature. As a result, many interpretations of natural phenomena were given. Huh .
Today many complexities of nature seem to be happening according to simple rules.

For example:- the simple rule of solar eclipse is that when the moon is moving between the Earth and the Sun and all three are located in a simple line, the solar eclipse is visible.
At the time of full solar eclipse, there is darkness in the day.
One definition of physics is:
"Physics is the branch of science in which matter, various forms of energy and their interactions with matter are studied.

Whai is Matter :- Every object that has mass, which occupies some space, and which is directly or indirectly experienced by the senses, is called Dravya(Matter).
For example:- stones, iron, gold, air, cotton, water, molecules, atoms, electrons, etc. are matter.

What is Energy: Energy is the physical amount which has the ability to do some work.
Heat, light, sound, kinetic energy of matter, power, magnetic energy, nuclear energy, etc. are different forms of energy.
Earlier it was believed that matter and energy are mutually independent and there is no correlation between them, a great scientist named Einstein discovered that the matter and energy are basically the same amount, they are mutually
transformation can be done, that is, mass can be converted into energy and energy into mass.
There is a correlation between these:
Energy = mass x (speed of light in vacuum)


 E = mc2

In signals. So the latest definition of physics is as follows, "Physics is the branch of science in which energy, mass, their interactions and transformations are studied. goes ."

Recommended book of physics in India for class 11 and 12:-

Books                                       Publication / Author

Concepts of Physics:-                 HC Verma

Objective Physics:-                    D.C. Pandey

Fundamentals of Physics:-        Halliday, Resnick and Walker