Class 11 Physics Physical World Fundamental Forces in nature

Fundamental Forces in nature

The forces which we see in our day to day life like muscular, friction, forces due to compression and elongation of springs and strings, fluid and gas pressure, electric, magnetic, interatomic and intermolecular forces are derived forces as their originations are due to a few fundamental forces in nature.

A few fundamental forces are:

  1. Gravitational Force: It is the force of mutual attraction between any two objects by virtue of their masses. It is a universal force as every object experiences this force due to every other object in the universe.

  1. Electromagnetic Force: It is the force between charged particles. Charges at rest have electric attraction (between unlike charges) and repulsion (between like charges). Charges in motion produce magnetic force. Together they are called Electromagnetic Force.

  1. Strong Nuclear Force: It is the attractive force between protons and neutrons in a nucleus.It is charge-independent and acts equally between a proton and a proton, a neutron and a neutron, and a proton and a neutron. Recent discoveries show that protons and neutrons are built of elementary particles, quarks.

  1. Weak Nuclear Force: This 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.This particle was first predicted by Wolfgang Pauli in 1931.

Below table shows difference between the above forces.

 

 

 

Name

Relative Strength

Range

Operates among

Gravitational force

10–39

Infinite

All objects in the universe

Weak nuclear force

10–13

Very short, Sub-nuclearsize (-10-16m)

Some elementary particles, particularly electron and neutrino

Electromagnetic force

10–2

Infinite

Charged particles

Strong nuclear force

1

Short, nuclear size (-10-15m)

Nucleons, heavier

elementary particles

 

Unification of Forces: There have been physicists who have tried to combine a few of the above fundamental forces. These are listed in table below.

Name of Physicist

Year

Achievement in Unification

Isaac Newton

1687

Unified celestial and terrestrial mechanics.

Hans Christian Oersted and Michael Faraday

1820 and 1830 respectively

Unified electric and magnetic phenomena to give rise to electromagnetism.

James Clerk Maxwell

1873

Unified electricity, magnetism and optics to show that light is an electromagnetic wave.

Sheldon Glashow, Abdus Salam, Steven Weinberg

Carlo Rubia, Simon Vander Meer

1979

 

 

1984

Gave the idea of electro-weak force which is a combination of electromagnetic and weak nuclear force.

 

Verified the theory of elctro-weak force.

 

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