Light is a form of energy that causes the sensation of sight. The bodies, which emit light by themselves, are called self-luminous bodies. When light falls on non-luminous bodies, it gets scattered in all directions by which they can be seen. Our eye is self-luminous body because it emits light, i.e. emitting microwaves by producing electromagnetic radiations.

Light in the form of mechanical waves emanates from the source and travels through the all pervading ether medium

Matter absorbs or gives out energy only in the form of quanta. A quantum of light is called photon. Light is propagated in the form of waves but when interacting with material particles of minute size such as electrons, it exhibits particle nature.

Visible light forms part of radiant energy. The visible spectrum wavelength extends from red (7,500A) to violet (4000A). (1A = 10pow(-10)m)

The wave nature of light travels through vacuum in the form of electromagnetic waves. Electromagnetic wave propagation consists of electric and magnetic fields vibrating in mutually perpendicular directions and transferring energy a wave motion in a direction perpendicular to both these fields.

The transition from one state to another is a 'quantum jump'. If the second one has the  greater energy (in a higher level), the organism must assimilate energies from outside to make  the transition possible. To a lower level it can change spontaneously, spending the surplus of  energy in radiations. In the process of quantum jump, The molecular energy is converted into the  energy of an electromagnetic field (external).

Emission of light from an atom of an element consists in transition of the electrons in  the atom from higher (initially excited) levels to lower energy levels.

Stimulated emission is caused by the presence of a radiation (wave) of suitable  frequency reacting with the excited atom. The important features of this type are all the  radiations are exactly similar to the inducing radiation, have same phase, same polarization  state, same frequency and same direction.

The vibrations of particles in all pervading either medium will cause a light wave. Light  is an electromagnetic wave, which does not require any medium. The sunlight reaches earth in the  form of electromagnetic wave, which does not require any medium.

The amount of energy generated when using microwave is 'E'. Energy has been equated to matter by Einstein's equation E=M(c*c). 'E' is the energy generated, when totally mass of all neurons  'M' is involved in producing EMF energy from our brain for transmission to other brain which travel with a velocity of light 'c'.