physics i unit

8/11/2019 Physics I Unit

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Chapter - I

PHYSICAL WORLD


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Science

The word SCIENCE originated from a latin

word SCIENTIA, which means To Know.

Today, the beneficiaries of science are not

human beings but also other forms of life.

It is the systematic study of nature and

natural phenomina.


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Scientific Method

Science develops through Scientificmethod.

It involves..

The search of basics of science to as muchdetails and depth as possible.

The use of the knowledge so gained to predict

new phenomena or modify the existing theory.

Observation, Qualitative and Quantitativereasoning, etc


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PHYSICS

Physics is a branch of Natural Science

The word PHYSICS came from Greek.

The meaning of PHYSICS is nature. It explains the diverse physical

phenomena on the lines of different

conservation principles and basic laws.


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PHYSICS

Modern Physics and Classical Physics are the

names of the two domains respectively.

Classical Physics Modern Physica

Mechanics

Thermodynamics

Electrodynamics and Optics

Atomic and Molecular

Physics

Nuclear Physics

Fundamental Particle

Physics

Quantum mechanics

Quantum Electrodynamics

Condensed Matter Physics

and Nano Physics


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Scope and Excitement of Physics

Scope of Physics is truly vast

Covers Magnitude of Physical Quantities

like Length, Mass, Time, Energy, etc


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Length

Length is measured as 10-14m or even less

It is in the nuclear region

Also have distances of the order 1026

m. It corresponds the end of known universe.


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Time

Small measures : 10-22Sec.

It is the time of passage of light across the

nucleus.

Large measures : 10 18Sec

It is the time to cover 1026m travelling with

speed of light.


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Mass

Very small : 10-30kg

It is the mass of electron

Very large : 1055

kg The mass of the whole universe.

Terrestrial phenomena is somewhere

middle of this range.


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Physics, technology and Society

Physics, technology and Society


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PHYSICS, TECHNOLOGY AND SOCIETY

Physics paves the way for tomorrow's

Technology

18thCentury - Theoretical heat engine led

to the discovery of steam engine

19thCenturyWireless communication

Technology led to basic laws of electricity

& Magnetism

20thCenturyStudy of semiconductors

led to the technology of silicon chips, and

nano chips


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FUNDAMENTAL FORCES IN NATURE

Forceis needed to push, pull, throw,

deform, break or even change the motion

of objects.

Pulling forceTension

Pushing forceCompression

In Addition, several kind of forces-

Gravitational, muscular, contact force,frictional, elastic, buoyancy, etc


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Different forces arise from a few

fundamental forces in nature. They are

i. Gravitational Force

ii. Electromagnetic Force

iii. Strong Nuclear Force

iv. Weak Nuclear Force


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Gravitational Force Mutual attraction between any two objects

Universal

Newtons Universal law of Gravitation :

Every object in the universe attract each other

with a force. This force is directly

proportional to their masses and inversely

proportional to the distance between them.


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Gravitational Force It is of long range

It does not depend the intervening medium

Weakest fundamental force

Plays a key role in universal phenomena

formation and evolution of stars, galaxies

and galactic clusters)


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Electromagnetic force

Electric Force / Electrostatic force :

It is the force between two charged particlesat rest.

Attractivefor Unlike chargesand Repuslive

for Like charges


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Electromagnetic force It is the force experienced by a moving

electric charge in a magnetic field

Its also of long range

Does not require any intervening medium

The medium modifies its magnitude

Its nearly 1036 times greater than

gravitational

Dominates in atomic and molecular

phenomena


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Electromagnetic force Effects :

Chemical reactions, thermal and other

properties of materials, Tension, Friction,elastic force, etc


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Strong Nuclear Force Force between protons and neutrons

It binds them in the nucleus

Strongest fundamental force

100 times grater than electromagnetic force

Charge independent

Electron doesnot experience this force

Its of short range

Its responsible for nuclear stability


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Weak Nuclear Force Appears only in some nuclear processes

Eg : decay

During this, the nucleus emits one electronand a neutrino (uncharged).

Greater than gravitational force

Smaller than strong nuclear force Range within the nucleus


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A COMPARISON

Force RelativeStrength

Range Operates among

Gravitational

Force

10-38 Infinite All objects in the

Universe

Electromagnetic

Force

10-2 Infinite Charged

Partilcles

Strong Nuclear

Force

1 Very

short

Nucleus

Weak Nuclear

Force

10-13 Very

short

Elementary

Particles

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