PARTICLE PHYSICS

 

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Four Fundamental Forces of Nature

Particles in nature are subject to one or more of the four fundamental forces:

Gravitational Force | Electromagnetic Force | Strong Nuclear Force | Weak Nuclear Force

 

Gravitational Force:

gravitational force

This is a force that acts between particles, which have mass.

This force is always attractive and is very weak unless the masses involved are large.

The distance over which gravity can act is infinite. Its size is inversely proportional to the square of the distance between the particles on which it acts (i.e. as the distance between the particles increases, the force of gravity decreases)

This force is very important, as it keeps the planets, stars and galaxies together; its effect on elementary particles and the structure of the nucleus is negligible.

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Electromagnetic Force:

electromagnetic force

This is the force that binds electron and protons together in atoms and binds atoms and molecules together in ordinary matter.

Electormagnetic forces also appear in the form of electrostatic force that acts between charged particles and magnetic forces that act between movingcharged particles

It is the force on which all modern electric and electronic technology is based.

This force can be attractive or repulsive.

The distance over which this force can act is infinite. Its size is inversely proportional to the square of the distance between the particles on which it acts (i.e. as the distance between the particles increases, the force decreases)

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Strong Nuclear Force:

 

This is the strongest of all the forces, however its range is very small.

It is very powerful and is responsible for binding the nucleus together, against the repulsive electrostatic force between the protons.

Leptons do not feel the strong force at all.

 

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strong force

Weak Nuclear Force:

weak force

This force can be felt by all particles and when very near eachother it is the force between particles that are not subject to the strong force.

It is much less powerful than the strong nuclear force.

The beta-decay of nuclei and the decay of a neutron into a proton occur via the weak force.

 

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