chapter 1 class 11 physical world notes

Chapter-1                                                                                                                                         Class-11

                                                                   Physical World

                                                                                                 By Kartik Dagur

1.       What is Science?

        Answer: The knowledge which humans have gain through observations and experiments when                                 organised systematically is called science.

2.       What is physics?

        Answer: Physics  is the branch of the science which is devoted to the study of nature and     natural phenomenon.

 Scope and excitement of Physics:

The scope of physics is microscopic physics, modern physics, mechanics, thermodynamics, electrodynamics optics.

Physics in relation to other Sciences:

-Physics in relation to chemistry.

- Physics in relation to biological science.

- Physics in relation to astronomy.

- Physics in relation to other sciences like biophysics, geology, aceanography.

- Physics in related  to  society.

- Physics in related  to   mathematics.

The development in physics have a direct impact on society:

                -Development of telephone, telegraph, telex enable us to transmite message.

                 - Development of radio, t.v, satellite for communication.

                 - Exploration of the new Sources of energy.

                 -Advance in electrons, computers, leasures for the transport like truck, bus, motor cycle etc.

Fundamental forces in nature:

-Gravitational Force: it is a attraction force between two bodies. It is directly proportional to the product of mass of bodies and inversely proportional to the square of the distance between bodies.

Therefore:

Properties of gravitational force:

-it is a attractive force.

-it is weakest force in nature.

-it is operate over very long distance.

-it is obey inverse square law.

-it is conservative force. These are central force.

Weak nuclear force:

These are the forces of interaction between elementary particles (electron, anti-nutrons etc) of short life terms.

Properties of weak nuclear force:

-it is weak force and 10 to the power 25 times stronger then gravitational forces.

-it is exist between elementary particles.

Electromagnetic force:

It is the force between two point charges. According to coulomb law the attractive or repulsive electromagnetic forces between two point charges is directly proportional to the product of charges and inversely proportional to the square of the distance between of them.

Therefore:   

  [EO = electrical permitivity of free space].

Properties of electromagnetic force:

-it is repulsive or attractive in nature.

-it is obey inverse square law.

-these are central forces.

-these are conservative forces.

-if the charged particle is in rest then the force is called electrostatic force. If charged particle does not move the force is called electromagnetic force.

-it is 10 to the power 36 times stronger than gravitational force.

Strong nuclear force:

The force that hinds neutrons and protons together in a nucleus is called strong nuclear force.

Properties of strong nuclear force:

-it is 10 to the power 38 times stronger then gravitational force.

-it has smallest range.

-do not obey inverse square law.

-it is attractive force.

-non- central force.

-non- conservative force.

Nature of physics law:

Some physical remain constant in time these are called conserved quantities. In the classic physical deal with the following conservation of laws.

-law of conservation of energy: the sum of the total energy of all kinds in the universe remains constant. It can be transferred from one to another.

-law of conservation of linear momentum: According to this law in the absence of an external force system remains unchanged.

-law of conservation of angular momentum: According to this law if the total external tarque acting on the system is zero than angular momentum of the system remains constant.

-law of conservation of charge: According to this law chare are neither created nor destroyed but transferred from one to another.

So friends or students these are notes for class 11 chapter 1. These notes are very best for learning and easy language.

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                  How To Create A Blog And Earn Money

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Story Of The Magical Bird

                            THE MAGICAL BIRD

Once there was a brave captain of a ship.  He had made many successful sea voyages. He had even lost his one leg in his  Adventures. When he set out on another voyage to find the Lost Treasure, he had to face the rough sea.  His ship was damaged.

         He felt responsible for the safety of his men.  He was a good captain. He prayed to God to bless their journey. After a windy and rough weather,  the next day the sun shone brightly to the sailors surprise on the sail of the ship was perched a big bird with beautiful coloured Wings.  It was a God send. They gave food and water to the bird.

        The bird flew  and showed way to the ship. Soon the captain show an island.  They anchored the ship and followed the bird.The trusted bird showed the captain the way to the lost treasure.  The captain disturbed the Treasure equality amongst his man. He and the bird become trusted friends. The last sea voyage made the captain a richer men.

Article On Rapid Urbanization

           RAPID URBANIZATION-A PROBLEM

The massive influx of people from small towns and villages into Metropolitan cities has various adverse consequences  on all sections of society. The fast paced growth of urban population has caused a great strain on the capacity of the Municipal Corporation to provide even the basic utilities like housing,  water, electricity and sewerage.

           It has also led to the  springing up of unauthorised slums at every available space.  The rise of these unplanned squatter settlements are a clear index to the unbearable living conditions that immigrants  face. This problem needs to be tackled on an urgent basis. The government must plan on how to create more job opportunities in villages and small towns so that the people living there do not feel the need to move to cities.  

        

        The government should plan its strategies  and investments in such a way that the rural population is provided with Economic opportunities other than agriculture.  Only then can the false lure of cities as lucrative places for a better life can be removed from the minds of the rural population.

Effects Of Urbanization On The Environment

There are many effects of Urbanization.

1. Increasing of population at a place.

2. Everyone people know that more people more pollution.

3. To complete daily supplieses peoples effect Environment.

4. It is not possible to get more jobs at one place.

5. Peoples left their fields in villages that is an effect on the Environment.

Factors Of Urbanization

1. one of the most important issue is no jobs.

2. so peoples attract toward cities.

3. No fields for farmering.

Essay On Dowry System

India  is a Male dominated society where the evil practice of Dowry has become very common. The woman has been relegated to a secondary place and has a marginal importance in the family. She has been reduced to a thing, not a human being. The recent spate in the cases of the dowry deaths exposes the hollowness of our social and cultural system the true of married women and cases of bride burning are rampant in lower middle class urban families. The birth of female child is still considered to be a burden on the parents.  Beauty, good features, culture and qualification may be important but a fat dowry overweighs  all these considerations.

     Even in the modern world where women are marching ahead in all walks of life, the evil practice of the dowry system continuous. Naked materialism  and consumerism  have only Increased  the appetite of the Dowry  seekers.  That Dowry  amount depends upon the social and economic status of the prospective bridegrooms.  Demands for cars, bikes, music system,  ACs  is costly furniture and growing in the marriage market. But the greed of dowry seekers remain unsatisfied.

      Bride-burning is not a rare phenomenon  in India. The Anti-Dowry Act,  1976 must be strongly  implemented for eradicating  the this social stigma.  The dowry  seekers should be socially boycotted and given strict punishment..  Public and voluntary organisations should come forward to root out this  social evils from the society.