1. 3.1: Properties of Light Text pp 92-92
Chapter 3: Light & Atoms
3.1: Properties of Light
Text pp 92-92
SNBook pp

2. Electro-Magnetic Wave (energy)?
What is Light?
Particle (matter),
~or ~
Electro-Magnetic Wave (energy)?

3. A History of Light
People have been discussing what light IS for millennia.
Rays or Streamers
Socrates and Plato thought light to be “filaments,” that went from the eye to the object.
People still commonly think of light as a ray.

4. Particles
Democritus and other Greeks thought of light as a stream of particles.
Modern scientists call light particles Photons

5. Waves
Sir Isaac Newton discovered that light behaves like a wave.

6. Newton on Light
Although Isaac Newton did experiments in which he discovered light formed patterns just like a wave, he preferred the light-as-particle theory.

7. Other scientists built on his experiments and found that light consisted of two transverse waves:
One magnetic wave, one electric wave, moving in tandem.
Light is an “Electro-Magnetic Wave”

8. Then along came Einstein…

9. Einstein on Light
In 1905 Albert Einstein discovered how light was formed in He called the process the photo-electric effect.

10. Light is created as little particles, or packages of energy called photons…
…So which is it? What is LIGHT?!??
Particle or Wave?

11. Light is both a Particle and a Wave!
Most scientists now believe that light exists in a dual nature. It is both a particle and a wave at the same time.
This state of existence is called: The Wave-Particle Duality