LIGHT - THE PERPETUAL MOTION

   

    To understand light, first we should understand maxwell's equations.  There are four equations.  I have given them in  words form below.

   1. Single positive and negative electric charges exist.  The electric field flowing out from a charge is always proportional to the quantity of the charge.

    2,   There is no single magnetic pole.  only magnetic dipole exist (north and south).  The magnetic field lines starting at any point around the North pole will always loop back and ends in south pole.  Hence the total field diverging out from a magnetic dipole is zero.
     
     3. A changing electric field creates changing magnetic field which encircles the electric field and also acts perpendicular to it.

     4. A changing magnetic field creates changing electric field which encircles the magnetic field and also acts perpendicular to it.

     If the statement 3 happens, the statement 4 will follow and vice versa.  Consequently a wave called electromagnetic wave will arise.  The light is a form electromagnetic wave.

     When a ray of light is emitted from a source, it will continue to travel for ever, yes for ever. Source of light (LED,Sun) does not contribute to the motion.  It is a self sustaining motion as stated by Maxwell,s third and fourth law. For a bullet, the speed and energy is given by the gun. A bow is responsible for the arrow's motion. But the lamp is not responsible for the light's motion.

    We know, star light travel through universe for millions of years.  So far, No one has seen a light ray coming to a screeching halt. 

     Hence  the light's motion is a perpetual motion.