What is light? 1

Light is Energy  Light is nature's way of transferring energy through space.  Remember--light is energy.  Light travels very rapidly, but it does have a definite speed.  In a vacuum, the speed of light is 186,282 miles per second (or nearly 300,000 kilometers per second). 2

Where does light come from?  The Sun and stars.  HOW IS LIGHT MADE?  It all starts with the ATOMS found inside the sun and stars. 3

Light & Atomic Structure  Light comes from ATOMS.  Therefore we need to know something about the structure of atoms to understand where light comes from. 4  A nucleus surrounded by electrons that orbit it.  Like the planets in the solar system, generally, electrons stay in the same orbit.

Light & Atomic Structure  However the Electrons can be made to jump into a higher orbit.  If you add energy to an atom (heat it up), the electrons will get excited and jump to larger orbits.  When atom cools, electrons jump back down to their original orbits.  As they jump back, they emit light, a form of energy, as a photon.  SEE NEXT SLIDE AND THE DIAGRAM. 5

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