SCIENCE AN ENRICHED DOMAIN

Humans have always been curious about the world around them. Since time immemorial physical world and natural phenomenon has fascinated humans . The tendency to observe and relate various phenomenon has eventually led to the endeavour of science.

  • What Is Science?

Science is a systematic attempt to understand natural phenomena in detail, depth, and use the knowledge so gained to predict, modify and control phenomena. Science is exploring, experimenting and predicting from what we see around us.

  • What is Physics?

Physics is the basic discipline of natural sciences which deals with the study of matter, motion, behaviour of space through time and related entities of force and energy and fundamental laws of nature.

  • Etymology:                                                                                                  

Physics comes from a Greek word meaning nature. Its Sanskrit equivalent is “Bhautiki” that is used to refer to the study of the physical world.  

  • What Physicists do?

Physicists try to explain diverse physical phenomena in terms of a few concepts and laws.  The effort is to see the physical world as a manifestation of some universal laws in different domains and conditions. 

For example, the law of gravitation (given by Newton) describes the fall of an apple to the ground, the motion of the moon around the earth and the motion of planets around the sun.

 Similarly, the basic laws of electromagnetism (Maxwell’s equations) govern all electric and magnetic phenomena.

INFLUENCE OF PHYSICS IN SOCIETY & TECHNOLOGY

  • The connection between physics, technology and society is remarkable with various examples . The discipline of thermodynamics arose from the need to understand and improve the working of heat engines.
  • Invention of Steam Engine , Telephone , Bulb made great impact on human civilisation.
  • Physics is the study of nature and natural phenomena. Physicists try to discover the rules that are operating in nature, on the basis of observations, experimentation and analysis. Physics deals with certain basic rules/laws governing the natural world.

MAJOR CONTRIBUTION OF PHYSICS

The contribution of most eminent scientist has revolutionised our world bringing entire humanity together.

SCOPE AND FUN IN PHYSICS

Physics is the study of the basic laws of nature and their manifestation in different natural phenomena. Physics has lots of scopes. Broadly , two major streams of physics are shown below.

Macroscopic Domain:

It includes phenomenon at laboratory, terrestrial and astronomical scales.

Classical physics deals with mainly macroscopic phenomenon. It includes subjects like Mechanics , Electrodynamics,Optics & Thermodynamics.

Microscopic Domain:

The microscopic domain deals with the constitution of matter at minute scales of atoms and nuclei, their interaction with different probes such as electrons, photons, and other elementary particles.

Subjects includes : Quantum Physics , Nuclear Physics

FUNDAMENTAL FORCES OF NATURE

There are  four major fundamental forces of nature :

  • GRAVITATIONAL FORCE : The gravitational force is the force of mutual attraction between any two objects by virtue of their masses.
  • ELECTROMAGNETIC FORCE : Electromagnetic force is the force between charged particles.
  • STRONG NUCLEAR FORCE :The strong nuclear force is the strongest of all fundamental forces, about 100 times the electromagnetic force in strength.
  • WEAK NUCLEAR FORCE : The weak nuclear force appears only in certain nuclear processes such as the β-decay of a nucleus.

PROPERTIES OF GRAVITATIONAL FORCE:

  • It is a universal attractive force. Every object experiences this force due to every other object in the universe.
  • It obeys the inverse square law. It varies inversely with the square of distance between the bodies.
  • It is a long range force which means it can act at large distances also.
  • It is the weakest force in nature.
  • It is governed by Gravitational Law.
  • It doesn’t need any intervening medium to act between bodies.
  • It plays a key role in the large-scale phenomena of the universe, such as formation and evolution of stars, galaxies and galactic clusters.

PROPERTIES OF ELECTROMAGNETIC FORCE:

  • It is both attractive and repulsive in nature. Like charges repel and unlike charges attract.
  • It is a long range force.
  • It inversely varies with square of distance.
  • It is governed by Coulombs Law.
  • Charges in motion produce magnetic effects and a magnetic field gives rise to a force on a moving charge. Electric and magnetic effects are inseparable – hence the name electromagnetic force.
  • It doesn’t need any intervening medium to act between bodies.
  • It is stronger than gravitational force and it dominates all phenomenon in atomic and molecular scales.

PROPERTIES OF STRONG NUCLEAR FORCE:

  • The strong nuclear force is the strongest of all fundamental forces, about 100 times the electromagnetic force in strength.
  • The strong nuclear force binds protons and neutrons in a nucleus.
  • A nucleus will be unstable due to the electric repulsion between its protons but it still holds stable due to this strong nuclear force which binds them together.
  • It is charge-independent and acts equally between a proton and a proton, a neutron and a neutron, and a proton and a neutron
  • Its range is extremely small, of about nuclear dimensions .
  • It is responsible for the stability of nuclei.

PROPERTIES OF WEAK NUCLEAR FORCE:

  • The weak nuclear force appears only in certain nuclear processes such as the β-decay of a nucleus.
  • In β-decay, the nucleus emits an electron and an uncharged particle called neutrino.
  • The weak nuclear force is not as weak as the gravitational force, but much weaker than the strong nuclear and electromagnetic forces.
  • The range of weak nuclear force is exceedingly small. It’s a short range force.

COMPARISON OF FORCES ACCORDING TO THEIR STRENGTH :

UNIFICATION OF FORCES

Unification is a basic quest in physics. Great advances in physics often amount to unification of different theories and domains.

NATURE OF PHYSICAL LAWS

  • In any physical phenomenon governed by different forces, several quantities may change with time. Conservation principles is very important to describe the observed phenomena quantitatively.
  • For motion under an external conservative force, the total mechanical energy i.e. the sum of kinetic and potential energy of a body is a constant.

The familiar example is the free fall of an object under gravity. Both the kinetic energy of the object and its potential energy change continuously with time, but the sum remains fixed.

CONSERVED QUANTITIES:

  • A quantity is said to be conserved when it doesn’t changes with time.
  • For example; If dy/dt=0  , then y = constant.

CONSERVATION LAWS

A conservation law is a hypothesis, based on observations and experiments. It is important to remember that a conservation law cannot be proved. It can be verified, or disproved, by experiments. An experiment whose result is in conformity with the law verifies or substantiates the law; it does not prove the law.

Various Conservation Laws :

  • CONSERVATION OF ENERGY : It states that the energies remain constant with respect to time and changes from one form to another form of energy.
  • LAW OF CONSERVATION OF MASS : This law is related to chemistry which states that the total mass of any substance undergoing a reaction remains constant.
  • LAW OF CONSERVATION OF MOMENTUM : It states that the rate of change of momentum of a system is conserved if the net external force is zero.

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