Class 11 Physics Physical World – Fundamental Forces in Nature

Fundamental Forces in Nature

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Four fundamental forces in nature are:

  1. Gravitational Force
  2. Electromagnetic Force
  3. Strong Nuclear Force
  4. Weak Nuclear Force

1.    Gravitational Force

The gravitational force is the force of mutual attraction between any two objects by virtue of their masses.

  • Due to the mass of the bodies
  • Attractive in nature
  • Weakest fundamental forces
  • Governs by Newton’s universal law of gravitation
  • Range is large – plays role in large scale

2.    Electromagnetic Force

Electromagnetic force is the force between charged particles.

  • Force between charges
  • Attractive (opposite charges) or repulsive (like charges) depends upon the nature of charge
  • Second strongest among the fundamental forces
  • If at rest – governs by Coulomb’s law
  • If in motion – motion of charges produce magnetic field, and magnetic field give rise to force
  • Acts over large distance

3.    Strong Nuclear Force

Strong nuclear force that strong force binds protons and neutrons in a nucleus.

  • Force that binds protons and neutrons in a nucleus – responsible for the stability of nucleus – neutrons and protons are made of elementary particles called quarks, so strong nuclear force can be an attractive force between quarks
  • Attractive force
  • Independent of charge: same for proton -proton, neutron – neutron, and proton – neutron
  • Strongest among fundamental force
  • Acts only in low range – inside nucleus (10-15 m)

4.    Weak Nuclear Force

The weak nuclear force appears only in certain nuclear processes such as the β-decay of a nucleus.

  • Appears only in some nuclear processes like β-decay of a nucleus
  • Operates among some elementary particles, particularly electron and neutrino
  • It could be attractive or repulsive depends on the situation
  • Stronger than gravitational force, weaker than strong nuclear force and electromagnetic force
  • Applies in very short range in the order of 10-16 m

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