PHYSICAL WORLD

Physical world

 1.1 what is Physics?

 Science is a study of nature, in nature there are changes some of the changes are permanent and some or temporarily. Permanent change is also called chemical change, and temperature changes are called physical changes. In Physics we deal with temporary changes in nature. Science is exploring one ,the scientist do experiments  and predictions to develop theories.

 1.2 scope and excitement of Physics

 The scope of Physics can be understood by examining its various branches. In broadly   there are three domains

1. Macroscopic domain

 Macro means something big in size . Macroscopic domain includes phenomena in Terrestrial  and astronomical scales. Terrestrial means the things we see around us. For example human beings animals buildings trees etc. Almost everything that visible to us, which we can see with naked eye call terrestrial. Astronomical means, Sun and planets extra.

2. Microscopic domain

 The term micro means something very small in size. The microscopic domain includes molecular, atomic and nuclear phenomenon.

3. Mesoscopic  domain

 The term  Meso  means something in between macro and micro. Which deals with few  tens or  hundreds of atom.

 Let’s have a quick comparison between all the threes

 Anything we see around us is called matter, which is made with molecules and molecules are made with atoms finally atom consists of nucleus and electrons

Excitement of Physics

 Let's see what makes physics an exciting subject.

1. Carrying out interesting experiments in lab,

2. Discovering secrets of nature

3. Applying laws of Physics in practical life

1.3 physics, technology and Society

 Sometimes physics generate new technology and other Times Technology will give rise to new physics, both have impact on society.

 For example heat engine, which was discovered in 1700 after this heat engine was discovered the scientist studied the principles and the reasons which makes the heat engine works. And finally they discovered a complete discipline of thermodynamics. Which means the scientist discovered heat engine first and then they discover the principle behind it.

 Similarly some other Times physics come first and then it gives rise to new technology. For example the IC chip in our computers, this came into picture due to the rise of new technology that will study in our plus two classes. IC chips are formed from semiconductor physics. This means theory of semiconductor physics which gives rise to IC chips. Here  Physics come first after  leads to technology.

1.4 Fundamental forces of nature

 Force is a push or pull that can cause an object to change its velocity of shape. There are four fundamental forces in nature they are gravitational force, electromagnetic force, strong nuclear force and weak nuclear force

 1.4 .1 Gravitational force

Gravitational force is a Universal force, which does always an attractive force exist between any two bodies in this universe. Gravitational force depends on masses and the distance separated by the masses. Gravitational force is the weakest force in the nature and it is also the longest range force.

• It is always attractive.

• It operates in all objects of universe.

• Its range is infinite

1.4.2 Electromagnetic force

 As the name suggests electro-magnetic, it is the force between charged particles it can be attractive or repulsive.  a charged particle in rest  can produce electric field ,but a moving charge can produce both electric and magnetic field. The forces due to electric and magnetic field on a charged particle are called electromagnetic force. • It’s due to stationery or moving Electrical 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.

 1.4 .3 Strong nuclear force

 The strong nuclear force binds the nucleons (protons and neutrons) inside the nucleus. It is the strongest force in nature, but the range of nuclear force is very small. The strong nuclear force is independent of charge.

• Operate between Nucleons

• It may be attractive or repulsive

• Its range is very short, within nuclear size

• Its strongest force in nature

1.4.4 Weak nuclear force

The weak force, or weak interaction, is stronger than gravity, but it is only effective at very short distances. It acts on the subatomic level and plays a crucial role in powering stars and creating elements.

• Operate within nucleons I.e. elementary particles like electron and neutrino.

• It appears during radioactive beta decay.

• Has very short range 10^-15m.

• 10^-13 times than Strong nuclear force.